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I assume that the 4th Edition companion book will contain similar depatterning rules to those in the previous editions.

Can anyone point me out to me if there are any references to if repeated frequent use of blood oaths such as blood peace or blood promise can risk depatterning or if someone with an already weakened pattern makes a blood oath can it lead to negative affects. Or is depatterning only related to the use of blood charms?

I would say blood charms only.

As of right now, there aren't any plans to include depatterning in the Companion.

While I think there is a good idea there, and a place in the game to reflect the dangers of blood magic, I've never been fond of the mechanics associated with depatterning. Something like that may appear in the future, but likely in a rather different form.

That said, if you're going to use it, I wouldn't have blood oaths affect it at all.