bitcoin/doc/release-notes-31385.md

RPC

The submitpackage RPC, which allows submissions of child-with-parents packages, no longer requires that all unconfirmed parents be present. The package may contain other in-mempool ancestors as well. (#31385)

P2P

Opportunistic 1-parent-1-child package relay has been improved to handle situations when the child already has unconfirmed parent(s) in the mempool. This means that 1p1c packages can be accepted and propagate, even if they are connected to broader topologies: multi-parent-1-child (where only 1 parent requires fee-bumping), grandparent-parent-child (where only parent requires fee-bumping) etc. (#31385)