Easy enough to do with webCoRE or just one of the Smart Apps in the Market Place such as Smart Lighting.
In your case, I would just set up notification events for the sensors you want to monitor outside of SHM.
If Motion 1 changes to Active
Then Send Push Notification or SMS…
SHM has two options for monitoring-Home and Away
During Home, you can specify which sensors are active and the same as Away.
You could also create Virtual Motions and place restrictions on them to never be Active when you set up the parameters in webCoRE.
Such as:
Restriction (Only when Presence Sensor is Away)
If real Motion 1 changes to Active
Then using Virtual Motion
Can specify a wait time before (Active)
Set to Active
If real Motion 1 changes to Inactive
Then using Virtual Motion (Inactive)
Now use the Virtual Motion as the motion sensor in SHM
If you are new to ST then I would suggest learning webCoRE as it satisfies all of your rule engine needs once you get the hang of it.