The recommended procedure in that case is to ask the translator to create a return package (even if the file is only partly translated). You will be able to open the return package so that you have the latest version of the file. Then you can use the Update file function in order to easily replace the original source file in your project with the updated one you received from your client, thereby taking over all the existing translations from the previous file. Last but not least, you can send out the new package to the translator. 

Thanks Fleur! That is actually what I do... I was hoping for a miraculous solution to cut steps . But it is handy to share this procedure with everyone. Thanks!

What if you're working as a freelanc translator on a project and you have to update a sourc file in Trados 2021? Can you do it without having to create return packages?

What if you're working as a freelanc translator on a project and you have to update a sourc file in Trados 2021? Can you do it without having to create return packages?