Dunning Days

Dear All,

T-code: FBMP dunning procedure.

System allows intervals no. days.

My requirement is - 30 days / 45 days/ 60 days

How can do for first interval. upto 30 days no letter.

after that days interval is 15 days, its ok.

Is it possible to get like this- 30 days 1 letter, 45 days 2 letter, 60 days 3 letter.

Please guide me is any way to do this.

Thanks you

Regards

partha