PokerTracker

For a certain stat in my HUD (eg: 'Fold To PF 4Bet After 3Bet') I can choose (at HUD - Item Properties) the position I want to be considered:
SB, BB, BTN, EP, MP, CO or AllPositions.

I want somehow to be able to have summarized (cumulative total) values (eg: SB + BB) and display the appropriate value (and times/opportunities) of the desired stat.

Eg:
- the value of 'Fold To PF 4Bet After 3Bet' only for SB and BB positions (cumulative).
- the value of 'Fold To PF 4Bet After 3Bet' only for EP and MP positions (cumulative).
- the value of 'Fold To PF 4Bet After 3Bet' for all positions (cumulative) except SB and BB.
- ...

This would be very useful for me to can display it in my HUD and even available as a custom stat in my views/reports etc..

Maybe Kraada or somebody else can help me with a formula to build a custom stat or something ...
I hope this is somehow solvable for any stat I want to build this kind of customization.
Thanks in advance!

You would need to make custom stats for that. The Tutorial: Custom Reports and Statistics has a section on making a positional version of an existing stat.
To specify multiple positions instead of using position = x, use position > 7 (for blinds) or position < 2 (for cutoff and button) for example.

after that i could use my new stat in the HUD (and reports) or a rebuild-cache or something is strictly needed (or only recommended) ?

It depends on how big your database is really - stats should work without a cache rebuild but if you have a large database it will significantly help performance.