conditional detail sections

i have 3 detail sections (assume detail prints 5 lines)

detail a - prints every line
detail b - has to print n blank lines if detail a prints < 10 lines otherwise nothing
detail c - has to print at 11th line always

i cant have this at footer because another detail e and detail f

Thanksi have 3 detail sections (assume detail prints 5 lines)

detail a - prints every line
detail b - has to print n blank lines if detail a prints < 10 lines otherwise nothing
detail c - has to print at 11th line always

i cant have this at footer because another detail e and detail f

Thanks

What I am getting from this is :
You want 'detail a' section to be 10 lines in height even if it contains less than 10 records.

If you want this only once on each page then do the following:
Remove your 'details b' section.
Make Page Header 10 lines in height approx.
Go to Page Header's properties in 'Format' and Check 'Underlay following sections'.

If you want this effect more than once on each page then you can group your records and do the same settings as mentioned above to that group header.

Just keep in mind you have to remove 'detail b' section.