Restoring the wife's baby, she refuses to let go of. Nearing end of "like new" repairs.

1993 Volvo 850 GLT, Auto. Trans.
All fluids full & clean

Flashing up arrow on dash. The ignition 5-times & shifter "row" 15-20 times cleared the previous DTC 3-1-3.
Normal secondary road driving, flashing arrow returned after 3-4 miles driving.
DTC code 1-2-2 only. Cleared & repeated driving test. Each time arrow & DTC 1-2-2 returned.
So, looks like a new S1 Solenoid is needed.

QUESTION: Sine the PNP Switch DTC code 3-1-3 was an issue previously & many posters say likely to return should I go ahead and replace PNP Switch, S1 Solenoid, S2 Solenoid, SL Solenoid & Trans. Filter all at same time? I'm thinking with the time & hassle needed to change the S1 Solenoid I may as well do everything.

Any suggestions & opinions appreciated. Not crazy about cost of doing all, but at same time don't want to pay twice for same work.

THX
Bill