Is there formula to use as a guide when figuring out how much point weight will reduce the dynamic spine?  Does so many grains subtract a certain amount of spine.

I generally go by this rule of thumb:
"If your point weight is heavier than 125 grains, add 3 to 5 lbs for every 25 grains".

Anyone else have a general rule about this?

Not tryin' to cause any stink but how can you have a general rule like that when it takes more weight to weaken a stiffer arrow?  I'm not tryin' to be a smart--- or anything I'm just tryin to understand how this works myself.

I think he means subtract.

Actually he said it correct.  If you are trying to achieve the same spine and want a heavier point, in order too achieve the same arrow you need to add spine.

The inverse is also correct.  If you have too heavy a spine you can add 25 gr for every 5# of spine you want to reduce.

Mike