WOW sheltie

I kept Girl 2 named NiNi in my home. The only Boy we named BOY had aslo been kept at my friend Melvin 's home.
Since pups turn to 12 weeks old our two hopeful suddenly get awful front leg with the pastern joint turn in and front feet turn out. But if we put up them away from table (or ground) let them relax， They could straighten their front legs. When they naturly stand the problem is coming. Does it just growth stage problem? When it could be corrected? Or When I could sure this would be a fault to get them out to pet home?
We study a lot of information about this problem. And we now changed their puppy food into adult food. Now they are over 4 months old, this problem still confuse us a lot.
As shelties could make a lot of changes during their growth stage. Maybe the only thing we could do is waiting and blessing for our babies.