I just became a Silver and flew first time with my son last week.

We ended up splitting the PNR at T-24, checked in online. Bag benefit did follow my son but being able to choose E+ seat was a challenge. For 2nd leg of the trip, we weren't able to chose E+ seat ( was asking for payment ), but ended up getting the upgrade so it wasn't an issue, there were plenty open seats in first class.
For the return trip, same thing happened for the 2nd leg. I ended up calling the Premier reservation line because we weren't going to be upgraded, first class was full. I was on the phone for 15-20min for to have my son to sit next to me in the E+ section.

Is there a procedure that I should be following? I have to be doing something wrong.
Any advice or input would be greatly appreciated!

Thanks in advance!!!