Different datums and Geographic CS but same Projected CS

[Kostas]

Hi I have a problem to solve.

I have 3 shapefiles with the following characteristics:

Projected Coordinate System: WGS_1984_UTM_Zone_34N
Projection: Transverse_Mercator

Geographic Coordinate System: GCS_WGS_1984
Datum: D_WGS_1984

&

also I have 2 shapefiles with these:

Projected Coordinate System: WGS 1984 UTM, Zone 34 North, Meter
Projection: Transverse_Mercator

Geographic Coordinate System: WGS84
Datum: D_WGS84

The problem is that I can convert the first 3 to my country's PCS but none transformation appears when I  try the same with the other 2. Any suggestion at least to make the second group similar to the first? 

[VinceAngelo]

If the data all registers well, then the difference is due to string comparison on projection names, not actual coordref differences.  This is one of the few cases where clobbering the .prj is acceptable (save the old one, though, just in case).

- V

[Kostas]

Thank you for your reply but then what is the solution? When I am trying to convert the second group to my country's CS I get no transformation back, in comparison with the first group of 3! What can I -practically- do to make the transformaton equation appear and work?

[Kostas · Accepted solution]

OK. I think I found it. Although still no transformation appears. The solution obviously is to convert the second's group PCS to the first's (with the usual way via Project) and continue with my country's...

[VinceAngelo · Accepted solution]

Actually, if it's safe, then ProjectDefine is appropriate in this case (saves an extra Project).