There is no built-in way to do this as of Velocity 5.0.
The best bet would be to implement your own script that does port selection for certain STC, then creates and reserves the topology. Something like this:
1. Draw your topology as needed in Topology Editor, use concrete ports and concrete STC.
2. Save the TBML and replace IDs (values of "guid" attribute) of the STC ports with placeholders such as `PORT_TO_SELECT_1` and `PORT_TO_SELECT_2`. You will later replace these placeholders with actual IDs.
3. Select actual port IDs by fetching the list of ports via API. You may check whether they are already reserved for certain time by using POST /conflicts API in Reservation Service.
4. Replace placeholders from step (2) with the IDs you selected on step (3).
5. Import the topology into Velocity using POST /topology API.
6. Reserve the topology using POST /reservation API.
7. (optional) Delete the topology imported on step (5) not to pollute the instance with temporary topologies.
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