As your other granddaughters weren’t christened are they cousins to the youngest one rather than siblings? I imagine they will have had gifts from you over time and would understand the christening is for the baby. Your daughter in law may have her own plans in place so best not to spoil those. A chat about the day and children in general with both your son and daughter in law may help clarify. I do like the idea of a shared game for afterwards, you could ask your daughter in law if there is one she thinks would work. We’ve taken a couple of little books or colouring (pencils not felt tips) for our young ones to similar events but not for other children who may be there. Personally I’d steer clear of cameras, it seems to me most children are fine taking photos with their parents phones and older children are likely to have their own. Please don’t worry too much, a christening is less fraught than many occasions and I’m sure will be a lovely family time.
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