Uninvited Uncle Showed Up to Bridal Shower, Worried About Rehearsal Dinner

I recently had my bridal shower. Only the female family and friends were invited aside from my fiance, father, grandfather, and ring bearer accompanied by his father because he's 9 and came with my aunt and flower girl. My uncle on my mom's side asked if he could come - he asked via my mom, and my sister who was planning the shower politely said no. One of my aunt's was sick and unable to come and he then again asked if he could have her spot, my sister again said no, that's not how these things work. I was shocked when he showed up unannounced to the shower when we were eating. He walked over to me, mumbled a congratulations and then joined my fiance and father at they're table where he ordered food and drinks that we paid for. He didn't bring a gift and also walked up two my two sisters (maid of honors) and made a sly remark "what, I don't get a table name card?". Since we didn't send him a bridal shower invitation, he got the address and time information from my 94 year old grandmother (his mother). He also drove 2 hours out of his way to come to the shower. It felt very disrespectful.


Later that night, I spoke to my mom. I thought she would 100% be in my corner, but right off the bat, she defended my uncle, saying he just wanted to be included. My mom and I ended up getting into a big disagreement about it but are now on good terms. I told her that I was worried that he would randomly show up to my rehearsal dinner since I know he will be staying at the hotel (like most guests) the night before. My fiance and I chose a venue in the middle of NY and Boston, where the majority of our friends and families reside so everyone is technically coming from out of town. We are only inviting 30 guests to the rehearsal dinner and the only people not in my wedding party who are invited are my great aunt who is 96 and travelling from Canada and possibly my grandfather's brother who would be travelling from Holland with his wife. My mom does not want to be "involved in drama" so she refused to say anything to my uncle and I do not want to upset my grandmother who is elderly, my uncle tries to go through her to get invites by saying she said he can go but she doesn't know any better. My fiance and I have decided to include a note written specifically to my uncle to include in his invitation. We do not have the type of relationship with him where we'd call him (I'm not close with him and only see him once every year or two years if that). But I feel like I cannot do anything because he will just feel entitled and show up again and I will have anxiety leading up to my wedding. This is what we plan to include in the letter accompanied by the wedding invitation, I felt like I could not be too general because he would ignore it but do not want to come off mean - what would you do?
Dear XXX,
We are aware that you showed up to the bridal shower unannounced and uninvited and it did not go unnoticed. Let's take a moment to review wedding etiquette so we don't have a similar situation in the future.
The rehearsal dinner is a small gathering meant to be attended by members of the wedding party only and those specifically invited by the bride and groom. A separate invitation is required and event staff has been notified of who is on the list. The majority of our guests will be travelling to XXX the night before the wedding, and while we wish we could accommodate everyone - it's just not feasible.
We hope that you can respect our wishes. Please remember that the only people that control guest list are the bride and groom and you should reach out them directly if you're not sure where you stand, so it can be clarified. Thank you for your understanding and we look forward to celebrating with you at the wedding reception with the rest of our friends and family members.
-The Bride + Groom