You can help them for sure and can be named as an expert on the project, but as a current grantee you can't be the lead. We would suggest more of an informal advisor roll at this time.
Here is the policy regarding this:
Previous grantees, whose projects are complete and who have received an offboarding email from Ayesha, are eligible to apply for this CFP.
Current grantees may be eligible to apply for an expansion of their previously-funded work, or for a new idea, if they have completed their final reporting and had it accepted by the Program Team by August 31, 2021. Please note that the Program Team often has feedback on final reports: submitting your report is not the same as having it approved.
For current grantees that won't be ready by this deadline, don't worry - there will more more open CFPs to come. We intend to release these opportunities on a regular basis.
Thanks for the reply Chris!