Hello geozap,

Please take a look at the table of observations in the wiki, especially which types are allowed for the individual point dimensions.
https://software.applied-geodesy.org/wiki/least-squares-adjustment/observation

For your approach, this would mean:
for 1D, only height differences; for 2D, directions and horizontal distances; and for 3D, directions, slope distances, and zenith angles.

This is because JAG3D strictly distinguishes between a true 3D network and the 2D+1D approach. Regardless of this, however, such an approach is possible without any problems. You just have to prepare your observations yourself, as JAG3D deliberately does not automatically convert, for example, slope distances and zenith angles into horizontal distances.

I hope this helps.

Best regards
Pierre