Hmm..Since the root google plus login is the email that you do not want, I'm not sure if you can transfer it... However, this link might help a little:
support.google.com/youtube/topic/3024173?ref=plus&rd=1
More specifically, perhaps this link:
support.google.com/youtube/answer/3056283?hl=en&ref_topic=4628105
There is also a link about "transferring ownership," which might be something to look into.
In the past, I've contacted their support team and talked to a nice YouTube employee who really helped me. However, their support link that I had used (support.google.com/youtube/contact/ytgplus) no longer goes to the form that I had filled out for help, so I doubt that the emails I have are still used... =/
I have 2 email addresses for my YouTube channel. I have my Google login email, and then the 2nd email that is used on the channel's page. I look at the two emails as a second layer of security because I never give out my YouTube login email address to any other website, and they have different passwords. ^^ You can also link two Gmail accounts together so that you can easily switch between them. I personally wouldn't want my YouTube email account linked to where I get business emails because I get a bunch of "so-and-so left a comment" messages flooding the YouTube email account lol
You can also forward messages to one email account. This won't fix the login issue that you are mentioning, but if reading the emails on separate accounts is the issue, they can be forwarded and looked at together. ^^
