Kylie Jenner, Travis Scott, Khloe Kardashian, Angela White (formerly Blac Chyna) and Tristan Thompson all attended a ceremony Wednesday in L.A. to celebrate their little ones' accomplishments... True, Stormi and Dream all finished preschool.

Remember, a lot of the Kardashian siblings have kiddos who are around the same age -- 4 years old or so -- so it makes sense to see the parents here. The interesting thing, of course, is that Khloe and Tristan as well as Kylie and Travis are no longer romantically involved, yet they all played nice in each other's company.

Eyewitnesses tell us that Khloe and Tristan -- who are clearly on good terms -- were interacting the most out of anyone ... just sharing friendly conversation. We're told Kylie and Travis didn't appear to interact, but his family also joined the celebration.

Lastly, Blac Chyna (now going by Angela White) was also in the mix ... although our eyewitnesses say she didn't touch base with any of the Kardashians. No word if her baby daddy, Rob Kardashian, was there or not ... but Mama Bear was on the scene.

While it doesn't seem like Kylie and Travis have much to say, Khloe and Tristan continue to prove they're in a great place as co-parents. Remember, amid their frequent hang-outs and speculation that they're back together ... we've been assured that's simply not the case.

A real Kumbaya moment here ... ya love to see it.