Will fresh strawberries that have been chopped up and mixed with bc interfer with stabilty of a topsy turvy 3-D cupcake cake?

I only ever use buttercream in 3-D cakes but I really want to add strawberries this time, but don't know if they will effect the cake.

Oh thought of one more question, if I can't find good sweet fresh strawberries can I use frozen ones?
I use frozen to make my strawberry filling (pureed) but would they work if I thawed them and chopped them up?

I just don't want to make a cake that is doomed to fall or collapse.
Its going to be a white chocolate and strawberry swirl cake so I wanted to use strawberries in the filling, but not pureed or perserves .
Thanks in advance.

I don't think I would try it...fresh chopped strawberries added to buttercream will tend to juice up and make the buttercream less stable; and frozen berries tend to be mushy after thawing. In a sheetcake it would be fine, but in a 3-D cake you need stability!