You really only have 2 options in this,
Number one is to buy 2 CP tickets and then reserve a table for 2 and hope to get the same times. This poses a couple problems. First, you run the risk of not getting times close together as some restaurants are more popular and have less time choices. Second, you might not be able to sit together as it's two separate parties of 2. They might sit you together, this this is at the digression of the CM.
Number 2 is to just buy the 4 CP tickets. Yes, you will be paying more, but you'll all be sitting together.
What you could also do is sprinkle some pixie dust yourself and give your 2 extra CP tickets to a couple waiting in the standby line! It might make their vacation!