Jamie Lynn Spears may have realized she'd be pissing off her sister, Britney Spears, by showing off her Christina Aguilera residency drop-in ... so, she made sure not to in a recap.

Brit's famous younger sibling shared a series of sweet memories from her Sin City getaway over the weekend -- where she was enjoying a bachelorette party with a solid group of ladies. Lots of highlights in her IG post ... but interestingly, none capturing Xtina onstage.

Take a look at some of Jamie Lynn's standout snaps from the getaway -- she made sure to point out they hit up a 'Magic Mike Live' show .. and just hitting the town in general.

Yet, Brit's kid sis noticeably didn't post a single pic/vid from Christina's performance at the Voltaire at the Venetian in Vegas. In fact ... Jamie Lynn said her friend -- who is set to get married soon -- and the male stripper show were the only things worth leaving her kids for.

Of course ... there are a lot of complicated dynamics at play here -- which could have a role in Jamie Lynn's social media choices. BS and CA may go all the way back to the Mickey Mouse Club -- but fans have pitted the pop princesses against each other for decades.

It's not just fans though ... Britney and Christina have had rumored beef as well, for realsies. Whether any of that animosity has carried over into the 2020s is anyone's guess -- but it would appear Jamie Lynn was mindful of their history in going through her Vegas vacay.

On its face, you could argue JLS was just trying to keep the peace and not ruffle feathers.