Dear Erna,
Thank you for your question and please see our comments, suggestions below.
The same site, i.e. observing facility, may accommodate two or more observing systems, e.g., for multiple applications/programmes, such as for weather/climate, atmospheric composition, cryosphere, etc, therefore, there is no requirement to split systems that are installed in the same site, into two, or more, "Stations/WSIs".
It is up to each Member to decide how to assign WSIs to their stations, however we'd not recommended proceeding with separating the surface from the upper-air components of your stations considering possible operational implications, for example in relation to international data exchange.
In particular, we note that the two upper-air stations listed below (extracted from OSCAR/Surface) have been operating as one station each for many years (according to the records in the former Pub.9-Vol.A), using respectively the former WMO Index-Number 06060 and 06011 for both surface and upper-air observations.
For further reference please visit our related webpage here: https://community.wmo.int/activity-areas/WIGOS/implementation-WIGOS
Thank you very much, best regards,
The WIGOS Team