Add a line for existing Sprint Sero Customers! Get Same Grandfathered plan of $30/month (500mins fair and flex) - YMMV for some people

Ok, so I got my old SERO account converted to a SERO P account. I now want to add people to my plan and switch their plans to SERO P and then do TOLs.

Here's the scene: 2 people are current sprint customers in regular everything plans for $69. They are both currently in a contract on their own accounts. I want to bring them in then convert them and then do a TOL. Should be pretty straight forward. I did this in the past with reg SERO when it was more difficult to add lines and convert them. I already greased the skids and got an echat conversation, explicitly stating that I could add lines of service and convert them to SERO P. I realized from my previous experiences that I would need proof. Should I add lines with some generic plan then bring those two lines in? Or just try to do it one move? I dont want to order phones and stuff for these two lines because these people are not eligible for new phones at this point in time. They will be keeping their current phones, I'm just going to transfer them onto my plan for a month or so so I can convert them and then transfer them out.

Third person is not a sprint customer. On Tmobile prepaid. They can get a new phone and want the EVO. Should I order that phone, set up the SERO P on it then port his number over and carry him for a month or so then do the TOL? Or should I have him go get the phone, sign up with sprint, start with the everything plan and then add him to my account, convert it to the SERO P plus $10 (4G) and then do the TOL?

I know I can add upto 5 lines of service to my account and like I said, I have an echat conversation where it is stated explicitly multiple times with me summarizing that I can add lines to my account then convert those lines into SEROP.

I plan on using that if there is any issue when I call Sprint to convert these lines.

Any advice would be appreciated.

TIA!!