I've experienced similar with Portrait Place and the vouchers you get in the Bounty Bag. I booked a shoot for when DS was 6mth old and told them which voucher it was and that I was having my entire family (siblings, grandparents etc), they said that was fine.

On the day they tried to make me pay for the sitting fee as the voucher was just for the baby not anyone else. I argued with her and won but probably only because I told her that we'd spend around $800 on photos (as different families wanted group shots and stuff) and that they'd make up their money that way. In the end I think the total was $750.

Besides they make their money with the cost of the photos, what's a sitting fee or a $2 DVD/Cd to burn photos onto? Money hungry so and sos