1) Get the unmatached recs from F1 using the Key (column 1-3) of F1/F2
2) Get the matched recs from F1, however, the date(column 5-12) of F1 should not fall in the range of F2 dates(5-12 and 14-21).
You need a REFORMAT statement, and for SyncSort you need a FILL (or to use the default fill of space) and choose a byte somewhere on F2 which can never contain that fill value.
FIELDS=(F1:1,100,F2:1,1000) on your REFORMAT.
I will assume you want two output files.
For the first, use OUTFIL with INCLUDE=(startoffilltest,1,CH,EQ,C'the single byte fill character')
That, along with the name for OUTFIL, will get you all your unmatched F1s.
A second OUTFIL for the matches.
Needs INCLUDE= with reverse of above condition (NE) and the test the date as being within the range on the F2. The date from F1 on the REFORMAT record is at the same position as the F1, and the date from F2 is offset by 100 bytes.
From the JOIN you will get multiple records for duplicates on the match.
If you only want a single record in this case, you need to decide what you want.