Possibility to automatically update the subject of tickets via business rule

We see an interesting usage of the subject customization to make intercommunication with other helpdesk (of suppliers or customers).
IT could be fine to have a business rule that force the fact to update the ticket subject on some specific conditions with the one coming from specific sources.
In this way for example, it could be possible to make two helpdesk sync between them maintaining on the subject both helpdesk id. Actually is possible to edit the subject manually on every ticket. It could be fine instead to enable this feature automatically from some sources. This solves a typical issue between helpdesk systems unable to speak together avoid recreating of tickets at every reply