Marketpress global shopping cart and chained payments.

OK.. I am probably beating a dead horse, but I have only seen threads about a year old and nothing recent. When I first inquired about marketpress i was told that global shopping cart and chained payments were the answer to a main site, with sub sites each selling products. One check out for all stuff up to 10 stores, and I could take a % fee through chained payments.

Now that I have payed for a membership, i have marketpress multisite, gridpress, framemarket. However it appears that i cannot use global shopping cart with chained payments.

I have tried a workaround that was posted, but couldn't make it work. Please let me know if i should simply quit trying and move on, or if there are a few things that I could try...