Although LEHMAN will have some influence owning large part of the merging company, Lehman cannot take a complete control because like you said, the merging company will be very careful on how much share of the company they can afford to give up. This is unless, if the merging company is in deep trouble to exist by itself.
Why not just pay the taxes? ************ There are many possible reasons for other companies to merge with LEHMAN.
The best reason is always profit but other reason is the need of new additional capital for expansion if the company is projecting a good future business.