Kin you are a veteran of OD, there is no such thing as a personal low.
You have to chat to the Nana, she could be the Dad's Mum and be desperate for him to settle down with a naice woman not like that bitch of an ex who took him for every penny he didn't have.
Alternatively, you can sympathise with her daughter's predicament and grill her as to where the 'errant' exH hangs out.
Miranda I take my hat off to you, I would last approximately 5 nanoseconds with that.
Pom oh meet him, what the hell nothing ventured...