Sentence:  In a tense , closed-door session with Judge Smith , Rayburn attempted to work out a compromise : to <WSD>add</WSD> three new members to the Rules Committee ( two Democrats , including one Southerner , and one Republican ) . 
Meaning of the word marked with <WSD> tags:  make an addition (to); join or combine or unite with others; increase the quality, quantity, size or scope of