Suggestions for 4 generation posing

I'm doing an indoor, studio style family photo with 4 generations. One of the great grandmothers is a bit unsteady, and the family is reticent about having her hold the infant, while standing.


Seated while holding the baby would be much safer.


That being the case, I would appreciate some suggestions on posing the shot.


I have a small bench that can comfortably seat 2.


Great grandma on the bench, with ?? next to her?? Or, should I just mix them up a bit?


Then, the remaining family members standing behind her? Next to her? I need to keep the DOF in mind, of course, to ensure sharpness of all persons. I could slightly move the outside people a bit forward, if they were on the side, so they stay in the focal plane as much as possible.


(I'm using a 5D2 with an 85 f/1.8, stopped down to f/8. Light meter shows 160th sec @ f/8, ISO 100. I'm using 2 Alien Bees with 36 inch softboxes flanking the subjects).


Thanks.