Swapping out a roommate on a month-to-month lease (CA)

Hi, I am on a month-to-month lease for an apartment in CA; my sibling is also on the lease. Neither of us lives/stays at that unit regularly but we pay the lease on time every month as we have a rent-stabilized unit and do not want to lose it, and value being able to stay in that area whenever we want. We do not do anything shady like listing the unit on any short-term rentals or subletting it without permission; too much of a headache and the unit is just vacant when neither of us is staying in it. Now, we want to see if it would be possible to replace my sibling on the lease with my father, as he would like to come stay there for longer periods of time when we are not present (which we are fine with). Based on my light research this does not appear to constitute a new lease as one of the original renters (myself) would still be on the lease, but we wanted to see if this would be at all feasible or if there are any other legal considerations we should know of. Thanks!