This is why it's imperative that voices that call shenanigans on her talk of family harmony must be silenced. When declaiming about the confusing horrors children inflict on their poor mothers, no meddling voice that asks why the same applies to her and Phil must be allowed to influence the conversation. Granted, in their case, the argument actually traded back and forth is "No, YOU were favoured more, you just don't know it" because we have someone convinced that she was made into Phil's servant blissfully unaware that she's a stick used to bludgeon him over the head with about being rootless and shiftless. Also, given how stubborn they both are, it's pretty much a foregone conclusion that the only way the argument will end is when both of them change their addresses from "house" to "urn."
What Elly fails to remember is that from the get-go, she was all about how great it was to have a cute little girl and how Mike was simply supposed to lose on purpose all the time because Lizzie was soft and weak and defenseless and couldn't cope with defeat while he could take it. The problem is that, well, he couldn't take it. Here he was, being told to shut up about all the great things he could do so everyone could say how great it was that she just had to be there and be praised. For a soft, weak little boy, that's a damned lot to ask and he did not rise to the challenge. Just as he thought that 'cooperation' means 'having to obey Elly's every insane order without question', he wound up thinking that sharing means that he gives up everything and gets called selfish and bad for expecting anything in return.
What he still doesn't know is that for all of his talk of her hurting his feelings is that Liz is sure that he's the SON that shines in everyone's eyes. He got to do everything first and he got away with stuff she could never do because he's male. Why, he even got their house just for asking as if her feelings about the issue don't matter. She can keep on doing things to try to please her parents and it's still Ugly Brother's world and she's not even really living in it. Why, April can go off thousands of miles away and they talk about her as if she were present while she's just supposed to stand there waiting to be praised.
The sad thing about all of this is that just as it will take Phil and Elly dying for people to stop arguing about their horrible childhoods, it'll take the death of all three kids to finally put their sibling rivalry to rest.