This is exactly what I have been looking for. Any news on this feature?
On the Moodle doc I thought it says it was possible (see below in bold) - I probably misunderstood...
In manual allocation menu once a student has submitted work the teacher can then choose which other students get to access their work. If the student has not submitted any work the teacher cannot assign other students to access the work. However without anything submitted the teacher can choose which students’ work this student will access.