Guests declining to everyone but us

So I have family that originally stated back in December they could not go because of declining health and everything going on (they don’t fly only drive and they are out of state). This was told to my father who relayed the message to me. I took this information but still sent an invitation out of courtesy and because June was still a ways off and minds can change. A couple of weeks ago I bring it up to my dad asking what he thinks their final decision will be and he says they are the type to stick to their initial answer and not go back on it but I needed a more concrete answer but know I can’t ask until after my rsvp deadline mid-May. My dad got back to me and told me they told my aunt they could not come and feel terrible because they are the elders of the family and my dad told me not to stress anymore that I can mark them down as not coming. But without a concrete RSVP that states their decline or receiving the message myself I feel too nervous to cross them off the list. My fear is not planning for them any longer and then they show up and there’s no welcome bag or export card or table seating, and they’re not paid for because I didn’t prepare for them. I even reached out to my cousin who is the daughter of the aunt and uncle whose attendance I am inquiring about to see if she got our invitation because we mailed it to her parents house since no one could get an address from her and they live close but I got no response. I’m not sure if they are afraid to tell me their decline but I don’t think they know how relieving it would be to have a definite answer and not be left in limbo afraid to count them out because of no formal decline. I was also told that they are likely not to mail back an rsvp because they already said they weren’t coming back in December. (I honestly don’t see the trouble in mailing back an already addressed and stamped RSVP) But I think anyone who receives a decline that early (6 months out) and it isn’t formal would not take them off the list just yet because so much can happen in 6 months. I have another relative whose told my dad their spouse is not coming but I kept her on the list just in case they had a dispute or a breakup and things get mended in time for the wedding. (Even that is stressing me out because I also don’t want to take this persons spouse off the list and then they go back-sies. but they said they were coming alone now and the RSVP only had his name not hers as well unless people only put one name then IDK)


I guess I am looking for advice on how to handle this. Would you all take these declines given to other people as official declines and take them off the list or would you keep them on the list just in case? I wish people didn’t view declines as a bad thing to say to the host, I mean yeah it sucks to receive but the alternative of constant anxiety is worse.