I see a lot of positive comments for this post but I'd like to chime in and suggest that upping the equity is not going to solve the problem.

In once sense the engineer is making the same kind of bet as the VC. They don't know the founders too well, not sure if the idea is any good, its a big gamble. Buy unlike a VC, the company will be the engineers whole life until the idea proves itself or fails.

A few extra percentage points of a deal that will probably never happen is not really all that attractive.

The only solution is to raise more money and pay them more.