Funny: If a vampire only enters a house when there invited, how do they enter there own nyumbani when no one's home?

No one has to be invited to enter your own house.
So why would Wanyonya damu need be invited to enter their own houses?

haha they record themselves saying 'You can come in' and then they press a button when they get nyumbani and it says 'You can come in'. So then they can enter. (Obviously im not being serious :') )

Usually, when Wanyonya damu have to follow that rule, they either live in abandoned houses (which means no one owns it, so there's no one to give permission, and anyone can enter it) au they inherit houses from family members.

And from what I've heard. They only ever have to be invited once (sometimes once per entrance).

they own the house and thus have their own permission.

They only need to be invited if someone LIVING owns the house, so naturally if its their own, and they are Wanyonya damu (not living ,but undead) they dont need an invite. Niether do they need an invite to enter an other Wanyonya damu home.