Visio import of data for organizational chart comes in random order

As an example, one manager and 26 staff or subordinates with names a, b, c …z.

The layout is nice but the order of suborinates is random…eg c,z,r,g,h…etc

The order can be manually changed by moving each one….but this is tedious.

I have searched high and low as to why this can’t be controlled automatically, without success.

Any advice?