I have this below in as "default value" 

[frm-set-get day=[date format=d]][frm-condition source=param param=day greater_than=24][frm-math]([date format=n] + 3 )[/frm-math][/frm-condition][frm-condition source=param param=day less_than=25][frm-math]([date format=n] + 2 ) [/frm-math][/frm-condition]

It checks the current date, and if the date is greater than 24, its adding 3 to the current month [date format=n] + and if it is less than 25, its add 2 to the current month [date format=n] + 2

It works perfect until we reach the 25 oktober (month 10), then november (month 11) and december (month 12) is the same problem as then the return value is wrong - as there's no months that has that value (13+14+15)

So I need to rewrite/extend' the function to check if the month is a particular month (above 25 October) it then sets the value to dec(12) and when under 25 november it sets jan(1) and above 25 november it set feb(2) - the same goes for december. (below/above)

Hope it makes sense in what I would like to achieve :)  

Can anyone assist?