This has been requested numerous times and as a Handcyclist myself been tryign since 2016. Best thing to do is have a search before creating a new feature request as what needs to happen is the ones that are there alerady need to be up voted.
I think the most popular one is this one, get up voting.
https://forums.zwift.com/t/paracyling-added-to-zwift-handcycles-and-recumbant-bikes/44075