Selectable amount of wilds

I wish they would allow us to select a specific amount of wilds to be placed on a card instead of the whole inventory. If a clan mate is requesting a card i have zero of but got wilds of that rarity i would like to only put the amount i can donate to him on it and not the entire inventory of wilds. Like say he requests ice spirit but i have 0. And ive been saving up wilds to upgrade my knight i dont want to have to put them all on ice spirit just to donate 8.