Question on tenant changing roommates

[Mohamed Gaffoor]

We own a condo unit. Two tenants took the unit in January. Both names and their parents as cosigners are on the lease. One is "primary" (orchestrated the rental and is the one who Zelle's the rent every month and paid the security deposit). The secondary tenant moved out and the lease ends next Jan. The condo requires that they know about all occupants. Here are my questions:

1. I am assuming I can write a lease addendum adding the new tenant and removing the old one. Are there state specific forms (condo is in NJ) or can I use a generic lease amendment form I found online? It basically says I'm adding this tenant and removing this other tenant.

2. from the POV of the security deposit I can just keep the original tenants deposit for both I am assuming? Is that something that needs to be spelled out?