Adding a High 4th String

This is a simple but very effective tip for adding the 4th string to a re-entrant ukulele:

Fret Substitution:

Wherever you see a fret position on the 2nd string that is played on the 3rd fret or higher, you can substitute it with the 4th string.

Wherever you see a fret on the 1st string, add 2 frets to it on the 4th string and it is the same note

So a note played on the 2nd String – 3rd Fret is the same note as an open 4th string, therefore if I have two columns of finger positions, the first column being the fret on the 2nd string and the second column being the equivalent fret on the fourth string –
2nd 4th
3 = 0 (open)
4 = 1
5 = 2
6 = 3
7 = 4
8 = 5 etc.

To substitute finger positions from the 1st string to the 4th, add two fret positions to the 1st string.
1st 4th
0 = 2
1 = 3
2 = 4
3 = 5 etc.

Hope this helps.