Inventory needs to be by channel and group

We schedule our ads based on the number of ads in a group and channel. So we might have space in group 1/channel 1 for 10 ads and group 2/channel 1 for 20. Therefore, in the channel settings, we need to be able to say how many are allowed in inventory for each group. Then, when it serves the ads, obviously, it needs to use the number for the group and channel it's accessing.

Thanks.