group inside groups

Yes it is. Check this tutorial”: https://bdwm.be/wpcf7cf/how-to-set-up-conditional-fields-for-contact-form-7/

hmm, thanks for the answer, but in fact, the brief tutorial does not answer as the example given only talks about a simple non-cascading logic. am i right?

nope. check the form at the bottom. if you select “advanced fields” it will open the advanced group. if you then choose other for OS the ‘other’ group will appear within the advanced fields group.

right! thank you! that did it!

sorry, i forgot this: <3