Wow, an only child with 5 kids! You are really reaching outside your comfort zone!
I'm the oldest of four, my mom is the 7th of ten, and I have three kids. There is NO WAY you'll be able to treat them all evenly. Even if you magically could they'd still find a way to jockey for position. That's just how it is. Let it become the family joke. Lillian may complain that there are professional photos of the twins; the twins will complain that they never get you to themselves. Your oldest boys will complain that you made them responsible for everything and that they raised the little ones single handedly. You won't win, so don't try.
Enjoy your baby's baptism. Don't let all the shizzle suck the joy away from this brief time.
Me42, H40 D12, S8, S7 A revealed: 7/13 Sep 4/14; Agreed to D 1/15