If you had that combined with the dynasty fertility boosts, you could just land all dynasty members as counts in a large realm and make a TON of renown. I think that's way too OP. Of course, you can do whatever you want with a mod. But I think you can just look at it as your renown for a single realm is pretty much about the realm as a whole and not the individuals in it if they are the same dynasty. The dynasty is known if they are in the main realm pretty much by what the top liege of the dynasty does. If you have a king with a duke vassal of the same dynasty, is the Duke really going to affect the renown of the dynasty? I suppose you could say a little, but unless he/she does something particularly interesting, I don't think there's any reason they should increase renown for the main realm. Note that what that means is that I think a mod that gives renown for dynasty members who do something particularly interesting would be a good mod to have! In terms of landed dynasty members outside your realm, they would absolutely increase your dynasty renown by making you more well-known in lands you don't already occupy.