Younger Elise Reinier from Insidious II meets the Warrens. It could be confusing to have Ed show up however so they can say he's investigating some case (the case later seen in the inevitable Conjuring sequel) and just have Elise and Lorraine team up.
share...no.
The Warrens are actually real people. (Well, Ed passed away, but Lorraine is still kicking.) Having them randomly show up in a fictional movie universe (especially one that shares a common actor) would just be needlessly contrived and confusing.
And FURTHERMORE, this is my signature! SERIOUSLY! Did you think I was still talking about my point?