A tile with two small stations can be upgraded to any green tile with one station and the same exits.
1 55 14 888
2 56 15 887
A tile with one small station can be upgraded to any green tile with one station.
3 12 14 15 887 888 119
58 12 13 14 15 887 888 119
4 14 15 87 88 119
A tile with one large station can be upgraded to any green tile with one large station.
5 12 14 15 119
6 115 12 13 14 15 119
Below here there is no neat summary rule.
B 12 13 38
10 35 36 37 38 64 65
52 64 65 66 67 68