Nevets, let me begin by saying I don't know the contents of the black box that spits out stock grants. I'll also say that I appreciate you being open to good ideas from a good company.
Since the purpose of your inquiry is to establish a similar program at XJT, why don't you derive a sensible model. For instance, if we go from the premise that the stock grants are based primarily on each employee's earnings and secondarily on each employees longevity, you could establish a point system as follows:
Points = [0.80 * earnings] * [0.20 * YOS]
Add up all the points and divide by the total of all employees times the number of shares to be awarded would be the number of shares each employee would get.
Using your figures, that would be
[0.8 * 50,000] * [0.2 *3] = 24000 points for emp A
[0.8 * 100,000] * [0.2 * 10] = 160,000 points for emp B
If emp B has 1 tenth of 1% of all the points to be awarded and there are 50,000 shares to be distributed, then emp B will get 50 shares and emp A will get 7.5 shares.
That's one system and you may find another more universally appealing to your group.