Board Thread:Questions and Answers/@comment-5618861-20160401151943/@comment-24851346-20160426144826

They'd need incentive to do it.

The Demon Lord leaves most of the actual ruling to her subjects, and has absolute power in few places. She functions mostly as a figurehead. Her values are also widely accepted by 99% of monsterkind, so no reason to depose her. All the power she's accumulated is largely due to the demonic energy reciprocal loop she has with her husband, which is available to all monsters. The Demon Lord title grants her some literal power, but what advantage that would give a Lilim that they would want I don't know. Additionally all the Lilim are said to adore their parents, so there'd need to be a pressing reason to betray them.

So it seems that there isn't anything preventing a Lilim from deposing their mother, there doesn't seem to be any reason for them to do so.