Planning a wedding with unwell fil

Hi everyone,


Myself and my fiancé got engaged in September 2022 and we are currently planning for our June 2025 wedding.
In early 2022, my FIL was diagnosed with pancreatic cancer and prognosis was bleak, however after chemo and a full pancreas removal is doing well nearly a year on from the op (he was in hospital when we got engaged so it was very emotional!). When we started looking at venues and we found ‘the one’ we took my MIL and FIL with us and they were very keen for us to book it as they loved it just as much as us and even kindly gave us some money towards the deposit.
I am looking for some advice around a few things really, we chose 2025 as we are currently renovating our house and paying for the wedding majority ourselves so we can’t afford to get married any sooner. We are having a wedding for around 80 guests and I have family coming from all over to attend (my fiancé has a very small family). Recently, my MIL expressed to me that she had a gut feeling that my FIL wouldn’t make it to the wedding (the cancer does has a high chance of returning) and that all he wants to do is see us get married, and that she doesn’t know how she could go to the wedding without him there.
This is really upsetting to me as I have just this week asked my bridesmaids, we have booked accommodation and a photographer. I understand my MIL is thinking worst case scenario, we cannot afford to get married any sooner and my FIL is doing well at the moment. I now feel as though I probably shouldn’t mention the wedding planning to her now I know how she feels about it even though I had plans to include her in most of the planning as I am really close with her (including going to find a dress etc)
Wedding insurance I have seen so far won’t cover us for pre existing medical conditions and I don’t want to cancel our wedding on a what if basis. If my FIL does become poorly again we could get married at the local registry office with our parents as witnesses and go out for an intimate dinner following this….but I would also still want our original 2025 wedding to go ahead as this is something I have always dreamed of and a chance to celebrate with our family and friends. I am so excited for it but now I almost feel guilty for planning our wedding, even though my MIL/FIL were so excited for us to book it.
I guess the advise I am asking for is has anyone been in this situation before? Has anyone done a small registry office wedding due to family illness and then a bigger celebration later down the line? Can anyone also recommend a wedding insurer that may cover due to illness?
Sorry for the long post, a very worried bride to be x