simultaneous times; sunset times

[jointdoc]

Is it possible to have two items go on but not off (or off but not on) at the same time? I keep getting told I can't use a particular time because another device is using it.
More importantly, is it possible to set times as X minutes either before or after sunset or sunrise? Again, this seems like it should be a simple task but the options only seem to include a specific time or specifically sunrise or sunset but not the ability to set a time either so many minutes before or after sunrise or sunset.
Thanks.

[SeanM]

First, delete the schedule on the individual device.

Next, create a scene, with the devices that you want to turn On or Off at that particular time. Then, when setting up the scene, set them to the state you want.

The newer of the two Insteon apps has a Sunrise/Sunset offset feature under settings.