Transition from a natural to a sacramental marriage Please note: This question is not based on a real world case. I am not looking for pastoral advice but for a clearer understanding of the catholic position on marriage.


As far as I understand the catholic church's teaching there are two "kinds" of marriage: The sacramental marriage according to divine law which can be found among a christian couple and the non-sacramental marriage according to natural law which can for example be found among a non-christian couple.

Now let's imagine a non-christian couple marries (here in Germany you would go to some registry office for what we call a civil marriage): In the eyes of the church these two are now married in a non-sacramental way according to natural law.

Let's further imagine these spouses convert to christianity and are getting baptized. At what point in that process (if at all) does their marriage become sacramental?

I would imagine the following scenarios:


The easy one: They are getting baptized in the catholic church. The natural proceding now would be a standard catholic wedding to administer the sacrament. [Here in Germany that is in fact not unusual as we catholics have to first get a civil marriage and later, probably at the same or following day, marry sacramentally in the church.]
The more complicated one: They are getting baptized in some other (e.g. protestant) church. The RCC holds marriages between protestant christians as sacramental even if not administered in church. But as most protestant churches don't see matrimony as a sacrament they probably won't marry in church as they would have done in the first scenario. So when (if at all) does their marriage become sacramental in the eyes of the RCC?


Please note that I'm interested in two things: Is my general understanding of sacramental and non-sacramental marriages as laid down here correct according to RCC teaching? And if so how will the marriage of the mentioned couple become sacramental (according to RCC teaching) during their conversion to christianity?

I would especially like to have answers citing canon law or the catechism (whichever is applicable).



Clarification

I am indeed interested in what the RCC teaches about the sacramentality of the marriage of a non-baptized civil-married couple becoming (1) catholic or (2) protestant christians. Indeed for scenario (2) I am interested in the RCC teaching about within-protestant affairs. That one is sparked by my understanding that the RCC considers the typical protestant marriage as sacramental although most protestants do not.
A valid natural marriage becomes sacramental as soon as both parties are baptised. There is no need to do anything else after being baptised, either as a Catholic or in a denomination that observes the Catholic form of baptism (water and the trinitarian formula). If the baptism is not valid the marriage remains natural. The parties are the ministers of the Sacrament and exchange of consent is the essential element.


  1621 In the Latin Rite the celebration of marriage between two Catholic faithful normally takes place during Holy Mass, because of the connection of all the sacraments with the Paschal mystery of Christ. In the Eucharist the memorial of the New Covenant is realized, the New Covenant in which Christ has united himself for ever to the Church, his beloved bride for whom he gave himself up. It is therefore fitting that the spouses should seal their consent to give themselves to each other through the offering of their own lives by uniting it to the offering of Christ for his Church made present in the Eucharistic sacrifice, and by receiving the Eucharist so that, communicating in the same Body and the same Blood of Christ, they may form but "one body" in Christ.
  
  1622 "In as much as it is a sacramental action of sanctification, the liturgical celebration of marriage . . . must be, per se, valid, worthy, and fruitful." It is therefore appropriate for the bride and groom to prepare themselves for the celebration of their marriage by receiving the sacrament of penance.
  
  1623 According to Latin tradition, the spouses as ministers of Christ's grace mutually confer upon each other the sacrament of Matrimony by expressing their consent before the Church. In the tradition of the Eastern Churches, the priests (bishops or presbyters) are witnesses to the mutual consent given by the spouses, but for the validity of the sacrament their blessing is also necessary.
  
  1624 The various liturgies abound in prayers of blessing and epiclesis asking God's grace and blessing on the new couple, especially the bride. In the epiclesis of this sacrament the spouses receive the Holy Spirit as the communion of love of Christ and the Church. The Holy Spirit is the seal of their covenant, the ever available source of their love and the strength to renew their fidelity.
  
  III. MATRIMONIAL CONSENT
  
  1625 The parties to a marriage covenant are a baptized man and woman, free to contract marriage, who freely express their consent; "to be free" means:
  
  
  not being under constraint;
  not impeded by any natural or ecclesiastical law.
  
  
  1626 The Church holds the exchange of consent between the spouses to be the indispensable element that "makes the marriage." If consent is lacking there is no marriage.
  
  1627 The consent consists in a "human act by which the partners mutually give themselves to each other": "I take you to be my wife" - "I take you to be my husband." This consent that binds the spouses to each other finds its fulfillment in the two "becoming one flesh." 


CCC on Marriage


  Can.  1055 §1. The matrimonial covenant, by which a man and a woman establish between themselves a partnership of the whole of life and which is ordered by its nature to the good of the spouses and the procreation and education of offspring, has been raised by Christ the Lord to the dignity of a sacrament between the baptized.
  
  §2. For this reason, a valid matrimonial contract cannot exist between the baptized without it being by that fact a sacrament.


Jimmy Akin

While Catholics are required to follow the required form of marriage non Catholic's are not


  A defect of form case can only come into play if one of the parties to the marriage is a Catholic (who has not left the Church by a formal act).  In a case involving a defect of canonical form due to a wedding taking place “outside” the Catholic Church, the Tribunal must be able to establish certain facts including the following: that the Catholic party was bound by canonical form; that the Catholic party had not left the Church by a formal act prior to or at the time of the wedding; and that the marriage was never subsequently convalidated or otherwise rendered valid in the eyes of the Catholic Church.


Defect of form