Deleting Old Contact Lists, Campaign Engagement History, and Campaign Stats

Question One: Campaign Engagement History if you delete and then add a contact back: There are a lot of changes to our membership/email list every year. If we delete our old membership lists to remove inactive members/emails, both active and inactive members will be deleted. When we add our current membership list back, to keep our contacts current, will the campaign engagement for those active members / emails be available. For example: We have some active members that have been on email lists going back to 2016, when we delete those old lists, active members will also be removed (until we add a fresh membership list). We want to make sure that when we add them back that we will still be able to see their historical campaign engagement. We have done a couple of trial runs and it looks like the engagement history does "reappear" when an email is added back...but, we need to double-check before moving forward. Question Two: If we delete old contacts/lists, will that impact the stats tied to specific campaigns? For instance, we have a newsletter that we monitor open/click rates for and need to make sure that if we remove inactive contacts that it won't impact the original stats.