What “SP and RI Group Sharing” offers

With RISP (RI + SP) Group Sharing, you can define how these discounts are distributed across sub-accounts inside your AWS Organization, for example, by business unit, department, project, region or cost center. https://aws.amazon.com/blogs/aws-cloud-financial-management/control-your-aws-commitments-with-risp-group-sharing/
You define “groups” using AWS Cost Categories and then choose a sharing mode:
- Prioritized Group Sharing - within each group, discounts are applied to group accounts first; any leftover capacity spills over to other accounts in the organization.
- Restricted Group Sharing - discounts stay strictly within each defined group; there is no spillover outside the group.

Shared-discounts and the ability to disable them

The management (“payer”) account of an AWS Organization can enable or disable shared discounts for any member account. If sharing is disabled for an account, that account gets no benefit from SP/RI owned by other accounts. https://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/ri-turn-off.html#ri-turn-off-process

This means organizations have flexibility: they can disable sharing entirely (so discounts only apply to the owning account), or selectively disable for some accounts while sharing with others.

Why Umbrella rebilling does not support SP/RI group sharing / disabling SP/RI Sharing

Umbrella implements its own logic for SP/RI allocation - meaning Umbrella determines how discounts and usage get attributed across accounts according to its billing and cost-allocation rules.

Allowing AWS-native group sharing or discount-sharing toggles would conflict with Umbrella’s internal allocation logic. In other words, you cannot reliably combine AWS’s discount-sharing with Umbrella’s allocation - doing so would introduce ambiguity over which logic applies.

Therefore, Umbrella disallows enabling AWS’s SP/RI Group Sharing or disabling SP/RI sharing at AWS level, to ensure consistent, predictable allocation based solely on Umbrella’s logic.