TMZ claims separate baby showers were in the works for Rob K & Blac Chyna, but he had no idea!

TMZ has shared a new update on the drama between Rob Kardashian, Blac Chyna and the Kardashian sisters. For starters, Rob had publicly shared his younger sister Kylie's phone number in revenge against his family for allegedly planning a baby shower without inviting his pregnant fiancee.

This was reportedly a case of misinformation, as Rob had no idea about what was actually going on. Read below...Rob Kardashian and Blac Chyna are seriously on the outs, and Kylie Jenner got caught in the cross fire when she planned a baby shower for Rob and Chyna ... TMZ has learned.

Sources close to the Kardashians tell us Rob got pissed at his sisters Monday -- especially Kylie -- for what he considered a slap in the face ... the Chyna-free shower they were throwing. We're told the sisters only planned separate his and hers showers because Rob and Chyna haven't been speaking for months.

They briefly reunited for a dinner the night before their reality show premiered, but other than that ... they've been split.

Still, Rob was pissed when he learned BC wouldn't be at the shower -- so he skipped it, and dialed up some revenge by tweeting Kylie's phone number. Thing is ... we're told Chyna had agreed separate showers were best.

Rob wasn't told that until after the fact, and we're told he's still pissed, We're guessing Kylie will have to get that number changed.