Most of the rides will hold three One adult and two children...or two adults and one small child:
Dumbo
Peter Pan Flight
Snow White's Scary Adventures
Winnie The Pooh
Haunted Mansion
Big Thunder Mountain
Buz Lightyear
Astro Orbiter
Indy Speedway
Magic Carpets of Aladdin
TriceraTop Spin
* Barnstormer may be a little tight for one adult and two children
The Tea Cups will hold several adults and children.
R&R has room for two riders only...Space Mountian has room for three riders in each rocket. Mission Space holds four, Test Track would be three and three. (per car)
The other rides are larger and will hold like three and four people
or either are on boats.
I can't remember any others.
TinkandHook
With five children you may have to let the older children ride together one must be 7 and older if they are all to young to ride by theirself I'm sure you could ride one adult and three small (one infant) children...on most of the Fantasyland rides.
Both groups of 3 and 7 will be fine.
Hope this helps.