Lounge maxes out at 4. I had ADRs for 2 and 3, offered to just sit 5 at the 4 top instead of taking two tables because my kids aren't that big. They said it was against fire code and they absolutely wouldn't seat 5 at a 4 top. We used the two tables per our ADRs, they were able to seat us right next to each other.
Now, my 5th wouldn't have been a high chair but I would assume the rule with the fire code is the same. You should book the restaurant for 5 or try for overlapping lounge for 3 and 2.