bob52 said
Hi,

I need to create forms with user defined id as hidden fields. One possible solution is to create a form for every ID, but that seems like a bad idea since there could be 20, 50, 100 ID's and hence that many forms.

yup

Another solution is to pass the ID value to an already created form, which will somehow be caught by the ID hidden field created in the form. Although, I am not sure if this is currently possible?

it is. you could pass it on via the link that point to the page with the form:   page?hiddenID=123

Another solution will probably be to grab the already defined fields in the created form and reconstruct them with the addition of the ID hidden field and the value, using the insert_custom_cform functions.

My questions are:
1. Is it possible to pass values to an already existing form?

yes, see above

2. Could an already existing form be reconstructed using the insert_custom_cform function?

yes, but it'll be more coding work

3. Do you have any suggestions on how to approach this problem?

you could add an empty hidden field and use my_cforms_filter() in my-functions.php to set the ID at run-time in $track[...]

If there are other possible solutions, I would be happy to hear them.

Thank you!