We have in-app exchange service, which you may use in order to top up your wallet, using other cryptocurrency coins that you have. For example, if you want to top up your BCH wallet using your altcoins, you need to launch your BCH application, go to Exchange option, choose to top up using the altcoin, you may choose it either by the ticker or the title. Then you will see the address where you need to send your altcoins in order to receive BCH coins in your wallet. Pay attention to the minimum amount for exchange. Then you go to your altcoin wallet or stock exchange and make a transaction using this address, after some time you will receive BCH coins to your BCH wallet.