Here's a copy-paste from some correspondence I had with the comptroller's office:

Like other PTE subtractions, subtractions for coronavirus relief grants received by the PTE are passed to the member on the 510K-1, part C., line 5. The PTE will specify the source and amount of the grant on the K-1 part G.

Coronavirus relief payments received by a PTE and passed to a member do not need to be reported on the 502LU. Only Coronavirus relief grants or forgiven loans received by an individual themself should be reported on the 502LU.

So, if you don't need the 511, you should be able to file the 510 and report the subtraction appropriately (as an other subtraction).

Also, as an FYI to those who received MD loans that were converted to grants (COVID-19 Emergency Relief Loan Fund), that conversion took place in 2021 (despite the governor's announcement of the conversion in December 2020) and you'll therefore receive a 2021 1099, with a MD subtraction in 2021.