If all you're doing is adding content to a repeater field that's in the same form as the description fields, I would not use an PUT/PATCH API call that requires the form entry to be submitted and saved first. API calls require the data to exist in the database before you can edit it. This means the form needs to be submitted first. I prefer to handle requirements like this in real time with jQuery, but because repeaters are Ajax based, there are some complexities to address when doing it this way. See this for details: https://formidable-masterminds.com/repeaters-and-complex-jquery-operations/

Hi Victor,
in my master form i have around 1000 entries which have to be modified, so that the entries existing up to now, have the opportunity to enter data in a Repeater. The Purpse is: To give the users the chance to create Company descriptions in different languages.
The original single language was german and now we want present the information on a multilanguage site. WPML helpd me to prepare pages an views in up to 4 different languages. But the data itself has to be translated. My approch is, to put the fields which contain language sensitive data into a repeater.
I don't see a different coice, than to do it via scripting.
I select a set of data though specific views.
inside the view is a javascript call. In a codesnippet the data will be manipulated. Field copying and than the PUT statement which modifies the original dataset+the Repeater fields. The good point is: I have to enter only one repeater record.
What i found out is, i have to run a "kind of create script" (in reality an update to the Master) and after that an update process, which the can cpoy the fieldcontent. After that everything will be displayed basically correct (only one dropdown is not set correct). But I'm finally not sure if this is the right way. My update data which is sent via ajax is like this: (masterform is 84, repeater is 121, record.id is the specific master record ID, fvz_rpt_sprachen is the key of the repeater container) var upddata = {"form": 121};
upddata[record.id]={
"fvz_rpt_sprachauswahl": "deutsch",
// "fvz_rpt_sprachauswahl-value": "de",
"fvz_rpt_firmenbes": record["fvz_firmenbes"], 
"fvz_rpt_firmazuecg": record["fvz_firmazuecg"] }; // for any reason, the fields are not set in the first run
upddata = { "fvz_rpt_sprachen": upddata }; Any idea how it can be done in a single step?
Or is it neccesary to do it in 2 steps?