NBA Star Ben Simmons Sister BLASTS The Kardashians . . . Sides With TINASHE!!!

The drama between NBA star Ben Simmons, ex-girlfriend Tinashe, and his new GF Kendall Jenner just got even MORE explosive. Now Ben's sister is weighing on on the drama - and she's TEAM TINASHE.

Ben's sister Liv took to social media to BLAST Kendall Jenner. According to multiple online reports, Liv liked her brother with Tinashe, over the Kardashians. And the other day she took to social media to BLAST Ben's new Kardashian GF.

You see, the Kardashians LEAKED a news report that Ben was going to be "beefing up security" after a few encounters with Tinashe. And that was enough to get Ben's sister TALKING.

Look what she said on Twitter:

This is his sister Liv:

You see, what Liv is referring to is detailed in this TMZ report, basically what happened was:

Ben Simmons believed his ex, Tinashe, has been tailing him and showing up at the same places he parties with gf Kendall Jenner ... and it's gotten so bad he's seriously thinking of significantly beefing up security.

Sources close to Simmons tell us ... Tinashe's been suspiciously popping up regularly at places he goes with Kendall ... way past the point of coincidence. You'll remember, the singer showed up at Delilah Thursday, and a couple weeks prior she surfaced at Poppy in WeHo when Ben was there.

We're told Ben is convinced Tinashe cannot accept the fact he ended their relationship and has moved on with Kendall. He believes she's showing up to keep tabs on him so she can see if there's a chink in the armor between him and Kendall.

But apparently according to Ben's sister, this ain't true because she's TEAM TINASHE.

It'll be interesting to see how this one plays out.