I have the following question:
If A sends BTC to a stealth address of B, then B sends the same amount of BTC to the stealth address of C, will A be able to see that his coins are now on C`s stealth address ?
This is not the problem that stealth addresses (try to) solve. Stealth addresses can be posted online (e.g. for donations) without the person that it sending payment knowing how many bitcoin have already been donated. You can think of them like a new address for everyone that wants to send you coins. You however can post a single string.