Will your baby sleep in a stroller or at different place?
You said 3yo, I'm not sure if Flounders will work? Maybe drop your baby there before dinner, help settle down and then head over to dinner?
I snicker whenever someone calls him a baby. (My sister does that a lot - she hasn't seen him in a while.) He's 38 inches tall (I'm only 62"). He hasn't used a stroller since he was almost 2. So, I guess he's more of a pre-schooler and less like a toddler.
They won't take him at Flounders - when I registered him for kid stuff online they automatically barred him from that option due to his age.
He really needs to be in a bed at bedtime. We've learned this by pushing our luck too many times at holiday visits. I won't talk bad about him, but I'll just say that when he gets past that bedtime point he gets selective hearing and decides to stop following instructions.