I make my own gumpaste using Tylose powder added to homemade fondant. I have made a couple of bear figures and it they seem to sage in the back from the weight of them. What is going on? Do I need to add more Tylose to strengthen it???

I think it's because fondant w/ tylose just doesn't dry as quick as gumpaste. You could try adding more tylose that may help. I do the same thing. I add tylose to my mmf and use it like gumpaste. I've had several of my figures settle and get a bit plump .