Should we tell my father's sick family?

Here’s my family debate - so my dad isn’t super close to his siblings but they’re still his siblings , and my brother and I both think they deserve to know mt father is sick , my dad doesn’t want anyone to know he’s sick because most of his family is also sick and he doesn’t wanna add onto their problems - but I think they need to know . My sis thinks like my dad and is arguing that nobody should know because it’ll make their sickness worse bc of the sadness - since they’ve lost so much already ( 3 siblings died the last 2 years ) anyway - I think it’ll be worse to call them last minute and say “ the funeral is here and here” I think it would actually hurt them more because they did not get to say goodbye - or speak to him . And it will come by surprise. Also they will be SO SO MAD at us for not telling them. I truly think for many reasons that they should know their brother is sick ….

I’d like to know if maybe I’m

Wrong here : since my sister is stubborn asf and thinks we are wrong .