ASSIGN TWO ADOBE FORMS TO A PAYMENT METHOD

[Oumou]

Hello team, i would like to assign two adobe Forms to a payment Method.

i have tried to do this by following this path :

I selected the company code and chose '' allocate forms to payment method in company code''. Then i assign the first adobe forms for the payment method ''W'' under ''pdf based payment medium forms '' section. 

I wanted to assign the other adobe form under '' pdf  based additional payment medium form '' but this field is desactivated. As you can see below.. I cannot do anything there.

Can someone help me please ?