I could use some master advice. I have built and glued wood framing members for a bunch of spanish cedar storm windows. The four corners are connected by bridle joints. Photos attached. There is a rabbet on the inside edge of both stiles for the track to seat. There are vinyl tracks that sit on the inside edge of the 2 stiles. The single glass window panes are housed in an aluminum frame with plastic guide plugs that are in the upper corners of the panes, and ride/guide in the track on the stiles. Fairly typical set-up. Unfortunately I managed to narrow the full width of the completed window(s) by 2/16". That translates into the length from the inside edges of the stiles to be 2/16" less. That is causing the window pane to bind in the vinyl dust seal of the track as you try to move the pane up the channel track. There is too much forcing pressure for me to let it stand like this. I have already seen the corner plugs binding and snapping the corner plug piece. Disassembling the storm frame is not an option. Recognize that if I take 2/16 off the left inside stile, I also need to do the same to the rabbet. Otherwise the track will sit proud of the rabbet edge. I do not have to cut both stiles. I can choose one stile and do a 2/16" cut reduction. The inside edge (edge #1) is visible to the exterior so it needs to be clean cut. The rabbet (edge #2) is only visible to the interior of the window.
Options??: I could possibly attach a long guide fence and a router bit with bushing for edge #1 and then repeat at shallower depth for edge #2. Then use chisel to clean up last 1" at top and bottom of a stile. Hoping someone has advice for this or other options. Any "be careful" comments are appreciated.

TFF wrote:Photos attached.

Photos were not attached. Please try again. And a cross section view of the stiles might be helpful too. I confess I had to look up bridle joint ...

uploaded the photos

While I mentioned bridle joints (glued) hold the four corners they do not come into play with the 2/16" reduction procedure I have to execute. The reduction will only be on the left or right stile (choose one) section between the top and base rail. What I did not say is the length. I have two sets of windows. One is 75" height from bottom of stile to top of stile, the other is 55". I have many of each to modify. The stiles go full length as it is a bridle joint. That was required to give a clean exterior view of the window. Base and top join the stiles. Mortises in the stiles, tenons in the top and base.

Thanks for adding the pictures.

If it were me, I would probably use a router edge guide. You already have the outside edges of the frames against which the guide could ride. Make one cut with face of frame up, make other cut with face of frame down. While you say you could take 1/8" off one stile or the other, cedar should cut fairly easy, and I would probably take 1/16" off each side.

Attached is picture of one such edge guide:

Thanks for tip on upside, downside. I did not think of that. Actually I may have that edge guide but never used it. I will check

Easy solution... clamp a straightedge parallel to the edge you need to remove the 1/16 from exactly 1/16" less than the distance from your router base edge to the outside edge of the bit. Stop short of either end and with a sharp chisel trim the remaining small bits. Nothing fancy, nothing expensive just a straight edge.
If you have a plunge router your straightedge doesn't need to be very thick. If not you have to make the straightedge a bit thicker so you can rotate the router against the edge and downward at the same time.
Reset for the other side and you have removed equal amounts.

Thanks for the guidance.

what about using a rabbet plane and cleaning up the corners with a chisel ?

Actually I think the perfect tool for corner cleanup is a small bullnose plane with the front slipped off which I guess then makes it a chisel plane. When super sharp oh what perfection to cleanup those pesky corners. A marking gauge to mark the 1/16 trim and a few strokes with the bullnose plane first, slip the nose off and clean the corner. No noise no jigs no clamps have the job done before you clamp up the window frame. Five minutes at most unless it is a really big window.