Weighted average price

Hello,
I am trying to implement Dolibarr in my company, I have managed to solve all the problems that I have been having by buying external modules, but here I cannot find one that does what I need and I cannot find the possibility that Dolibarr can do it either.

It turns out that when I make a proposal to a client, most of the time, I don’t have the merchandise and I don’t know the exact purchase price, usually at the last minute of the day, I make the orders to the suppliers and there I already know, I put the order in Dolibarr with the cost prices but, the Weighted average price is not updated in the proposal, when I pass it to order, neither is it, and when I invoice, neither is the Weighted average price from before that purchase, I have tried to put the date of the order to the supplier before the date of the proposal, but does nothing.

Hello…
nobody knows
no paid plugin??