While learning Korean, is it a good idea to start learning Chinese in parallel? I started learning Korean last year, and by now I'm pretty confident with the basic rules of the game; I'm also pretty interested in Chinese, and I've heard that many Korean words can be split up in terms of Chinese characters: for example, 도서관 ("doseogwan") means library, and "doseo" should be associated to a Chinese word for book. The suffix "-관" is present at the end of words which denote a place, I don't know if this has a Chinese origin as well.

So I would naïvely think that starting Chinese in parallel could help me building up and memorizing a larger dictionary, and that already knowing the Korean phonetics could make my Chinese life easier. I should also mention that a similar question has already been asked here for Japanese-Chinese: I think in that case the learner would be more likely to get confused, because of Chinese characters being present (maybe altered in writing or pronunciation?) in the Japanese alphabet(s).

But: I admittedly know very little about both Chinese and Japanese, so I have no idea how sound these opinions could be. I welcome any feedback!

Based on your experience: could it be a good idea to start learning Chinese in parallel, right now? Would that be just confusing, ending up in a mix of both? Maybe somebody here tried and succeeded, or tried and failed - or know somebody who did.
I speak Chinese, Korean and Japanese and it's not the grammar but the vocabulary which is similar. I learnt Chinese first so expected Korean to be very alike due to reading that 60% of all Korean vocab comes from Chinese. I was shocked when I found Korean so alien but in truth it is similar - to Classical Chinese and not Mandarin. I started learning Cantonese recently and indeed the vocab is far more similar to that than Mandarin. E.g. 학 / 学 which is pronounced xué in Mando but hak in both Korean and Canto.  大 is dà in Mando but dae in both Korean and Canto so University is daehak in Korean and Canto but daxue 大学 in Mando. Learning Canto made Korean make more sense to me.

The other issue that I faced was the characters. Korean uses the traditional script so upon visiting Korea I was faced with not only Korean script but a multitude of shop names which they think look cool in the traditional Chinese script. So I was struggling with two scripts! 

In general though, I've enjoyed learning them side by side as they do inevitably compliment each other, yet are different enough to not confuse you. I got to the stage of learning a new word in Mando and then looking up the word in Korean to see how similar it was. I learnt that all Chinese words in Korean work with 하다 to make them a verb so essentially all 하다 verbs are Chinese, e.g. To regret = 후회하다 / 后悔 hòu huî. It becomes quite fun!

Hope this helps! 
Gareth