Hi madabouttheshow!
If you see Episode 10 again you will notice that the papers Pete, his brother and mother were passing around and signing were legal papers. They have that "legal blue" document holder as the last page.
So, there must be a lawyer involved in the estate.

It wouldn't surprise me to hear Pete's family has some secrets. The sons don't seem to respect their mother, or like being with her, but they are protecting her from knowing their dad spent all his money. Or how he spent all his money, maybe. She seems pretty vague about it all, although still asked for an explanation. I wonder if that was from her age and/or health, or if she had always been out of the loop with the family finances. That would fit with her social status and the times. It doesn't seem likely, but I always thought we might find out Pete was adopted. Pete seems very trusting of what his brother says. Maybe he has already checked it all out and made sure about the money. I say that because Pete doesn't seem the trusting type at work.

There is a lawyer involved - that's who told Pete's brother how bad the situation was. If you can, re-watch "Flight One," the episode in which Pete's Dad dies - the first scene with Pete and his brother in Mom's house has the brother telling Pete about it. I think it's obvious from his demeanor that the brother didn't know the money was gone. The relationship between Pete and his brother seems really close - that's nice because his parents were certainly icebergs.

Pete seems to be relaxed around only a few people - Peggy, his brother, Trudy his wife and Duck Phillips. I guess he does trust a few people.

Frankly, I don't trust Bud. There's just something crooked about him, I think. He seems to have the upper hand because he's Mama's favorite. Very odd this family.

I think the money was actually from Pete's mother's side of the family. She had some major real estate holdings (I think in northern Manhattan). I believe that's one of the reasons why Pete is untouchable in the firm - they wanted to use his family's connections. I don't think the mother knew how the father handled (rather mishandled) the finances.

Pete's mother is an upper class bigot. The fact that she shows disdain for a son who would dare to adopt a child and bring bad blood into the fold speaks volumes. Also, when Pete and Bud were laughing about offing their mother, one of them asked "Remember the Rope?" I looked it up and it was a 1948 Alfred Hitchcock movie about two classmates killing another classmate.

Ever since Peggy/Pete's son was born, and Pete and his wife have been having infertility problems, I've been wondering how the plot was going to wind around to Pete and his wife adopting the boy. I just know it's coming.