RtHW Stat Blocks in CoS.

With the release of the new Ravenloft book, there are new stat blocks for Ez D'Avenir and Rudolph Van Richten. Both of these characters are in the CoS, and can be destined allies to help you fight Strahd. Although, both of these (especially Ez) have very powerful actions and attacks. I'm worried that if I use these in the CoS, they could potentially carry some encounters by themselves. Any advice? 

Ally doesn't mean that they actually fight, just that they provide some sort of assist. They're not even the most powerful possible allies (that would be the mad wizard), though they are potentially available much earlier.