We let people give their details to us when they arrive using an elvanto form, but I've had to create a second form on google forms for families because when you click "add another family member", it just duplicates the whole form. All people want to do is add some child specific info, not enter ALL the family info again and again for every child. Here's a copy of the form I've ended up using instead. It seems simple but elvanto just can't do it.

When I add families as an admin in 'people' there's no issue. The functionality of keeping general family-wide info across family members without having to re-enter it for every child, is baked in there. It's just when people give their own info that the functionality becomes very clunky and we miss retrieving a heap of info.

Please make your form functionality more robust. It's the same thing with holiday clubs. I outsource to Group VBS Pro's forms to get the functionality I need. It would be great it if was all in the one place.