Getting to network placed documents from green-screen apps

Hello sages

I could use a helping hand with this:

For some time now we store customer PDF documents on a network share
directories,
tree arranged by customer No. this way:
Customers (Directory of all customers)
Cst0000001 (sub directory of Customer No 1)
Ord00001.pdf (order No 1)
Ord00044.pdf
Inv00007.pdf (Invoice No 7)
Inv00023.pdf
.
.
Cst0000002 (sub directory of Customer No 2)
Ord000020.pdf
Ord00005.pdf
Inv00002.pdf
Inv000055.pdf

Cst0000003 (sub directory of Customer No 3)

etc..

When a (green screen) user wants to display a certain PDF doc (say order no
44)
We construct an appropriate path like \Customers\Cst0000001\Ord00044.pdf
and call STRPCCMD to open it on his/her PC.
We also let users see all documents in a customer directory by constructing
a suitable path (like \Customers\Cst0000001\ ).

Now,
Users are asking to display customer's invoices only (or orders only or any
other sub set).
but using wild-cards with STRPCCMD like in \Customers\Cst0000001\Inv*.pdf
does not produce anything (it hangs).

Does anyone here know how it can be done?

TIA
Gad