Nothing. You can recibe only 1 gift.... 1 morale, 1 of red color, 1 green, and 1 skill point. You can have a million firends sending you morale boosters, but... you will recibe 1....
to have more boosters, just, see your matches, (+1 morale booster) change 1 player, (I think you will have one red booster...) don't have cards... and if you win you will win another thing, I think xD...
that's why you have to try to play 2 friendlies X day ...to see the match, do one change, fair play... and you will win boosters