Praise be to Allah.Breast-feeding a child over two years old will not have the effect of making him a relative (mahram). It is permitted to breast-feed one’s own child beyond two years, but two years is enough, as Allah says:
"The mothers shall give suck to their children for two whole years, (that is) for those (parents) who desire to complete the term of suckling . . ."
The reply to the rest of this question can be found under Question 804.