"This seems a fair deserving, and must draw me
That which my father loses -- no less than all.
The younger rises when the old doth fall." (3.3.23-25)
On their own, the lines mean:
It seems fair that I will get what my father loses
I'll get all of it because when the old begin to fall, the young begin to rise.
Within the context of the scene:
Gloucester hears that the French troops have already landed and he wants to help King Lear, even though it is forbidden and should not be spoken of. Edmund feels that a lot about Gloucester will eventually be revealed and as a result, he will receive all that Gloucester will end up losing. If Gloucester's power suffers, Edmund is able to benefit.
Connection to other parts of the play and/or major ideas in the play:
These particular lines especially reveal the cunning, deceitful mind that Edmund has. He only has his wants and needs in mind and does not truly care about his father's interests. He is mostly focused and stuck on revenge for what he was born into. He resents the fact that he is an illegitimate child and still is unable to move on from that detail. It again relates to the motif/theme of deception and how the characters can manipulate others because they have their own interests in mind.
My response to the lines:
I feel like Edmund does not truly deserve all that he thinks he does because he is so insincere. He is a selfish, greedy character and it shows that you cannot always trust everyone because there may be some motive that we are unaware of. He thinks that the only way for him to improve status-wise is if his family members suffer and that just reveals his true intentions of bringing others down so he can thrive.