There are ways to go exploring these awkward things in ways that get you some information (which I see as a birth right to know your bloodlines and family history that belongs to you publically and privately) and protect others from upsets as well as their rights. Much info is public and public record. This is your Grandfather ... a very close and solid blood relationship and he was actually married to your Nan.

I have similar "icky" things regards my Dad's side of my family. The "family" has intimidated some of my Dad's siblings and others into no contact or else we'll be all upset with you and treat you badly for it (and they did treat them badly and I felt like hell for it) ... this when my Dad's siblings, a cousin, and even my own sibling/s (some) wanted contact. They wanted contact and were in contact and great towards me "You're Joe's kid" but walked on eggshells should the rest of the family find out. I get enraged and sad to think how my dads siblings especially have been and are being treated. Still, in the end, I wasn't raised part of my dads clan, they were and are close. Can't judge too harshly I suppose. They have to deal with each other and have full histories of family life together behind them. I do understand this.

Strange and upsetting world to think how petty and intimidating some can be to those who laid their lives on the line for their freedoms and things ... my Dad had a relationship with me til his death, on the sly from his "other" family

Oh the tangled webs we weave, huh?

Anyways ... I will helps as I can