I tried to make changes to SPP allocations but if you do it...

I tried to make changes to SPP allocations but if you do it causes potential problems with how the product works that could be costly to investors.
I wasn't the one who started making changes first.
So I'm advising people not to make any changes, I would post the email here but I don't have permission to do so.
If you want to contact OnMarket as to why you shouldn't use the Corporate Action function you are free to do so.
Nothing sinister here, I can send you the email if you'd like?

You're missing the point, you're not supposed to choose which ones you'd like to participate in, it's a managed product.

OnMarket are looking at the possibility of allowing some flexibility in SPPs in the future as well as as reducing broker fees. You have to bear in mind this is a new product.