Hi Dirk,
I'm not aware to do this by VBscript but it might work using the merge model feature
using the "manually synchronize two objects" from the merge model window.
1) from your CDM, create a new PDM
2) set focus on your PDM, then go to Tools > Merge Model...
3) select new PDM as the merge source and click OK
4) when Merge Models window pops up, scroll through the changes you have made
5) select icon "Manually Synchronize Two Objects" and select column from the new PDM, and select Table from old PDM
6) the PDMs will merge, and may create a new generation links
hth
Stefan