How do I combine two monolingual yaml files (one for source, one for target language, similar to xml) in Studio for a partially existing translation project?

Question

How do I combine two monolingual yaml files (one for source, one for target language, similar to xml) in Studio for a partially existing translation project? 
 The questions essentially already says it all, my client has a database in Locale App, from where it's possible to export databases but only in monolingual format. Their support tells me that it should be possible to open/combine the two monolingual files in Studio and go from there. This is necessary since part of the project is already translated. The two files will match perfectly, that should not be an issue, I just simply wouldn't know how to try that in Studio, even being a proficient user... Actually the format doesn't matter too much, it's the fact that I would need to open/combine two files perplexes me :). 
 Many thanks for your ideas! 
 Laura

Paul · Answer

Laura H 
 Laura H said: How do I combine two monolingual yaml files (one for source, one for target language, similar to xml) in Studio for a partially existing translation project? 
 Is this to create a TM with the already translated segments? Assuming it is then just align the files, or at least the segments within them, to get your TM. Then use this TM to pre-translate the source and translate whatever's missing. 
 Studio 2021 has a filetype for YAML, and if you have an earlier version you can use this from the appstore: 
 https://appstore.sdl.com/language/app/file-type-definition-for-yaml/778/ 
 If this isn't the usecase then you'll need to explain what it is?

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How do I combine two monolingual yaml files (one for source, one for target language, similar to xml) in Studio for a partially existing translation project?