Please keep in mind.... the trauma of going to a new home and all that that entails can cause stress on an expectant glider which could cause her to cannabalize her joey(ies). Just something to keep in mind if you consider getting these new gliders.
As far as cage toy ideas....invest in some fleece...you can make all kinds of braided ropes zig-zagging across the cage for them to climb on.
A ball pit can be made fairly easily...a plastic bowl of some kind and them fill it with fun stuff. Plastic "golf" balls from WalMart or the Dollar Store. Army Men, Plastic Insects ect...again from the Dollar Store.
You can even fill it with scrap strips of fleece. I have both...one filled with plastic stuff...(even milk lids, water bottle lids, milk rings...snipped so they don't get caught in them) and one filled with fleece scraps.
Large Legos are a hit... natural branches....PetSmart has an array of climbing logs and ceramic "caves" for lizards that work quite nicely for gliders.
In the last pic...I got these yellow/green balls in the seasonal section of WalMart. They work great for hiding treats in for foraging. The treat stays in and the holes are big enough for little arms to fit in, or if your glider gets smart they learn to tip the ball upside down and dump the treats out. I got plastic chain from Lowes and it's attached from the top of the cage with a C link...then the ball is attached to the chain with a baby link which you can find in the baby section of WalMart.