There is mod, contains an NPC, who have the key and rights to Breezehome.

She is in the Playerfaction, Whiterunbreezehomefaction, Whiterunfaction. She enters/leaves Breezehome often due her schedule.
Sometimes I noticed Braith wandering in my house. No anyone else, only Braith.

- A NPC closes the doors after entering/leaving it?

- How Braith can enter breezehome without the key? She is not in the proper factions, nor have relationships with anyone in breezehome.

I not modified Braith's packages, nor anyone else's.