Thanks for the responses guys. I have always paid the rent on time via post dated cheques. I've never gotten a receipt, however, I do keep records of the payments and the bank scans images of the cheques which I can view online.
The mother and sister have been involved in the affairs of the rental property even when my landlord was still alive. These two have never been pleasant and treated us disrespectfully from the get go. They've raised a fuss about some things in the past but when we demonstrated that we're not destroying the place they seemed to cool it a bit. Then my landlord died. We sent them a sincere condolence card as we were pretty shocked about the news (yes he was young, in his 30s). Now that some months have passed, they've started getting nasty about minor things and unreasonable about the solutuons. I really can't type out the whole story here in my phone because it would take too long. Suffice it to say, they threatened eviction unless we did something that isn't our responsibility to do. So we did it to appease them. Now they're picking on a couple small dents in the garage door. I don't know how they got there but they're only cosmetic and not very big. Still, I agreed to take care of it on my own dime. They insist it be now and when it took me a couple days to call them with an update she told me that was "unacceptable" that I hadnt called her earlier... seriously? Don't know who she thinks she is. Anyway, I ordered 2 brand new sections of matching, insulated garage door and planned to install them myself (simple bolt on procedure). This wasn't good enough for her. She demanded that I use the same company who installed it originally (someone she knows) and pay them 3X the price I ordered the parts for. I tried to explain that it's not rocket science but she didn't care. By this time she was screaming maniacally that I couldn't understand her and didn't even have a chance to discuss other options. She then hung up on me.
There are of course details I'm leaving out but that's the gist of the current dilemma. During that phone call I asked her if she wanted us to move out. She didn't answer the question.
I"d like to move out but she has post dated cheques for Sep 1 and Oct 1 + last months deposit. Nothing I can do about Sep but I plan to cancel the Oct cheque and reissue in original landlord's name if I decide to stay here. I also plan to request legal documentation about any transfer of ownership. I suspect they're just bullying right now to give the impression they're in charge when in fact they are not our landlord(s).
Sorry this post got kinda long as it is.