I'm going to try and keep this quick.
I am the product of my DF's second marriage. I believe his first marriage ended because he met my DM. They married when I was tiny. I know there were children from the first marriage but the divorce was very acrimonious and ended with DF's ex moving country and contact being lost.
I've never had any contact with any of my half-siblings. I think I could get contact details through extended family.
DF is now very unwell and may die soon.
Currently DF has said he sees no point in making contact now as too much time has passed but I keep wondering if I ought to get in touch. I don't know what I'd want if I were them, if maybe we'll all regret it if they don't have the chance to say goodbye. Or if it's none of my business/if they won't want to hear from me anyway.