Why don't you change the full site to just the nights that you don't have on the preferred site? Then you don't have to worry about them cancelling your duplicate reservation and once/if you are able to get those 4 nights on the preferred site you can cancel the full.
It is WDW policy that you cannot be booked into two or more locations for same party/same dates. If you needed 2 sites, they can note that on the reservation so that they are aware of the situation.
I'm sorry that you feel you were lectured, but it seems as though the booking agent was not concerned with policy and the guest service agent was. Truth of the matter is that you are "holding" a site that you do not plan to use, and that is taking away inventory from someone who really wants it. I understand that you don't want to move sites, I just think that you should make a decision...if you think you'll be able to get those 4 nights added to the preferred site, cancel the full site entirely...if you don't think those nights will open up, cancel the preferred. You can still always see if one or the other opens up for the length of stay, since it seems to be an "all or nothing" contigency for you. Or, you can split it like I mentioned and be assured that you will have a place for all 20 nights.
It is WDW policy that you cannot be booked into two or more locations for same party/same dates. If you needed 2 sites, they can note that on the reservation so that they are aware of the situation.
I'm sorry that you feel you were lectured, but it seems as though the booking agent was not concerned with policy and the guest service agent was. Truth of the matter is that you are "holding" a site that you do not plan to use, and that is taking away inventory from someone who really wants it. I understand that you don't want to move sites, I just think that you should make a decision...if you think you'll be able to get those 4 nights added to the preferred site, cancel the full site entirely...if you don't think those nights will open up, cancel the preferred. You can still always see if one or the other opens up for the length of stay, since it seems to be an "all or nothing" contigency for you. Or, you can split it like I mentioned and be assured that you will have a place for all 20 nights.