For MarketPress, can PayPal chained payments use new REST api's?

Hello, I setup PayPal chained payments in MarketPress with developer settings using Classic api system. Tests failed.

Troubleshooting store checkout revealed PayPal is switching to REST api’s (Classic phasing out). I prefer not to launch site until I know if/when MarketPress will support new system, and how it will work.

We require support to get chained payments to work in sandbox with classic api’s; settings are not in correct places. Need help sorting out live settings as well.