tracks south of Delanson to Altamont

And is there room in Delanson for an interchange yard?

You don't need to build a yard to interchange cars... all you need is a siding or runaround.

IIRC, there is a short siding with switch at each end just west of the Cole Rd control point.

There were several extra tracks (OOS) south of the mains at Delanson until the early 90s . There's plenty of room if need be.

But I doubt it would be needed. In the last few Guilford years, they would run a local down to Voorheesville and leave the cars on the siding on the north side of the main (think it was called the west siding) for a road train to pick up.