Oh I believe--there is a WAY easier way!
Next to the Quote button in the lower right corner of a post is a button that looks like a piece of paper and a set of quotation marks " and + sign. Just click that button for every post that you would like to quote. It will turn red with a - sign. If you change your mind you can click it again to "unquote" it.
When you are at the last one you want to quote click the Quote button or the Post Reply button and the posting box will come up with all the posts you have selected to quote.
I hope that makes your life easier!