Working in my own branch with changes in submodules

Dear GHC devs, I am currently working on my own fork of GHC ( https://gitlab.haskell.org/trupill/ghc), and as part of it I need to do some changes to the Cabal and haskeline libraries. However, since they are in submodules, I am not sure about how I can commit those changes, share them with others, and rebase my changes against the current HEAD for these submodules. Thanks in advance and kind regards, Alejandro