Engineers should automatically reclaim where they are and while
If an engineer stops he just reclaims in his range, no player commands needed. You can just mix up engis in you army, if your army holds over some reclaim, it gets eaten by the engi.
Just send an engi to a location and he will eat reclaim, no annoying patrol / attack commands needed, but you can ofc. still use it.
If someone don´t want auto-reclaim, you can turn it off.