Of course there will be examples of someone with wealth sharing that with stepchildren/siblings, but those cases are, in my personal and professional experience anyway, the exception to the rule. Bloodline planning, and yes it is referred to as exactly that, is and has been commonly utilised by those with the means do so. It preserves generational wealth so that it remains generational wealth. If some want to choose to share that’s their right, but equally choosing not to is just as valid a choice.
The reason the will has been repeatedly mentioned is that it clearly demonstrates the difference in how he considers the two. Another thing that demonstrates this is that, despite this being a child that has no relationship with her father, there is no question of adoption being on the table. This is also a man that completely accepts the position of his parents, and will not challenge them on it. These are things OP was aware of going on, but even if she wasn’t, as someone responsible for her child it was absolutely on her to find out exactly what his position was.
He has stepped up for this child beyond anything her biological father has provided, and she may view him as her father, but that doesn’t make him her father. He’s made is clear there are limits to what he is willing to provide to her, and OP, as well as anyone calling him and his parents every type of dickhead that walks the earth, have little choice but to suck it up.