How to avoid getting new t-addresses?

I’ve written a script to split funds up generated while mining. However when i send out part of the total zcash, it sends the rest back to a newly generated address, i understand the principle of HD wallets, but since i can no longer z_sendmany from the original address if the funds are now in the new t-address. Is there a way to send money in a way that doesn’t return my remaining funds into a new address?

Does sending zcash from a z_address have the same effect?

Thanks for any help in the matter.