WIBTA if my partner and I got married and kept it secret?

Me (33F) and my partner (44M) have one 2yr old child and another on the way. We have bought a house together a few years ago. We have been together for nearly 10 years. We are for all appearances act as a married couple already.

We are keen to get married on the date of our 10yr anniversary of getting together, which is in about 5months time. This date (and year) is important to me.

However, I’m from the UK so all my family are still there. Also, we are about to have a baby and so don’t have the budget for a big (or even small) wedding, nor do we have a great deal of time to plan.

Our plan was to get married very low key for between $500-$1,000 and just keep it between us (the place only has capacity for like 17 guests max anyway). Then in ten years time hold a proper party and invite all the family, potentially at a destination wedding or hold two parties (one here and one back in UK so everyone can come).

There are many considerations and I don’t want to offend anyone but figure it’s a wedding and most of the time that seems impossible to do anyway haha.

If we get married in 5 months, should we let family know ahead of time? A select few on my partner’s side of the family could join for the actual ceremony and we could have a small party after. Or do we keep it secret and throw a big party in 10years time on the same date?

There are grandparents in both countries that realistically wont make another 10 years, but honestly I’m more worried about my FIL/MIL and own parent’s reactions if they found out/even letting them know in advance what we plan to do.

A friend of ours got married during COVID then held a formal wedding a year or so later, always politely keeping it private that the documents had actually been signed the year before. I thought this was polite and respectfully done. But I don’t know if a 10yr secret is quite the same outside of a global pandemic limitations.

I like the idea of being upfront and giving the option for a handful of guests (which will be limited to this country) but it just seems so immensely difficult to navigate the expected hurt feelings.

What do we do?!