Only allow two addresses in checkout

[MrBaseball34]

I need to modify our checkout process where each user has 2 and only 2 addresses and they will be defaulted to billing and delivery.

I am also going to need to know how to default the data on the order page that shows the addresses to those two addresses and not allow them to change one for the other, i.e. set the delivery to billing.

We do want them to be able to update the addresses using the update link but not to add more if they already have 2.

I am OK with using the "Shipping same as Billing" option, however, and want that check box to stay.

I know about zelarg's Express Checkout Module and we purchased it, but it causes problem with our shop and I need
to get something working soon.

Please don't tell me to contact another developer. I am a developer, I just don't know PS well enough to accomplish this on my own and these forums are for peer SUPPORT, correct? I help out anytime I can, for sure.