'Proof' of family status for a 'family lift pass' ???

[CornflakeMum]

I've been told by our Chalet hosts in France that we need to take 'proof' of our family status in order to be eligible for the family-rate lift pass.

Any ideas what would be suitable?

DH & the kids have the same name on their passports, but I still use my maiden name (which may cause a problem?)

I can't think of a document which has all our names and address on?

Aren't there any suggestions from the chalet or on the ski pass website about what kind of proof could be provided? I suppose you could use copies of your passports and marriage certificate (and perhaps also your children's birth certificates, as that would have your names on it)...??

Driving licences, EHIC cards