So under separate interest DRO participant started receiving his benefits, and AP allowed to defer. I don't see any issues here. The issue would be: how to calculate AP benefits?
1. What is the latest participant's age AP can defer (NRD or RBD)?
2. How does DRO describe the timing of the split (at NRD or at participant's commencement)?
3. Is AP entitled for ER subsidy?
4. If AP is entitled to a subsidy, do you calculate AP's benefit at participant's commencement and actuarially increase it to AP's commencement? Or do you simply calculate AP's benefits at her commencement applying the same level of subsidy that participant would get at that time?