... a satisfactory alignment, and I can see why you are interested in double slips. I like your double outside slip, it will make an attractive bit of trackwork, assuming your house move allows you to keep it. I'm afraid this new function is for inside slips only, as you suspected. It will however let you create one at any angle, so if you want to try a 1:5 inside slip, you can. This is what a curved one on 2640mm radius looks like in 4-SF: 2_271601_180000000.png The inner slip road radius at 481mm/19" is rather sharper than anyone would consider for 4-SF! It could probably be eased a bit by creating your own design from scratch using custom switches, but probably not by enough to make it usable. On the other hand the outer slip road is 793mm/31.2" radius, so a 1:5 single-slip is feasible in 4-SF if given some contraflexure. The K-crossing check rail would still be a challenge. On straight track ...