You should not change parentIDs. These are set when a device is included and should not be changed after that. If you’ve already changed things, exclude the device to reset it to factory defaults and then include it again before you go any further.
Vesternet has a good explanation of scenes, associations, and groups. Also, though it won’t be helpful in the case of association groups, I really think that you should have a look at the guides and tutorials here http://support.getvera.com/
Associations and their groups are concepts local to the Z-Wave device. So, a group will exist only within the local physical switch that is being used to control other devices. In this case, Vera configures a group within the motion sensor and it tells the motion sensor that this group of devices are to be controlled directly by the motion sensor. The group exists only within the motion sensor, so other devices will use the same group number, but confusingly, they are not the same group. e.g. Group 1 in a switch is not the same group as Group 1 in the motion sensor. Both groups exist only within each physical controlling device and despite seeming to have the same name, they comprise different lists.
The actual Group numbers are decided by the device manufacturers. So they will vary from manufacturer to manufacturer. However, most manufacturers only support one or two groups and most number them accordingly Group 1 and Group 2. So, if your manufacturer’s manual doesn’t state which group numbers it supports, then Group 1 is usually a safe assumption to start with.
To have Vera configure an association group within a device:
[ul][li]Go to the Device Options tab of the motion sensor.[/li]
[li]In the Add Group field, type a 1 and click Add Group.[/li]
[li]Next click on the Set button that appears.[/li]
[li]Find the device that you would like the motion sensor to control(associate), in this case the lamp and check the box next to it.[/li]
[li]Click Save, at the bottom of the page.[/li]
[li]Click Back to Z-Wave settings.[/li]
[li]Click Apply.[/li][/ul]
At this point Vera should configure the device(motion sensor) with the association. But, it may take a while, since the motion sensor is a battery operated device that will sleep, making it unreachable from Vera until it wakes up. This may take hours, depending on the device.
To speed things up, follow your motion sensor’s manual to put the device in awake mode and in the Vera UI click “Configure node right now” on the motion sensor’s Settings tab. You can confirm that the device has been configured with the association by returning to the Device Options tab. The Current value should be the same as the Set to value(the node ID of the lamp).
Once properly configured, motion will turn on the lamp, regardless of Vera. Conversely, when the motion sensor untrips, the lamp with be turned off directly by the motion sensor.