I tried to workaround this issue by using virtual switch (this is basically similar to child devices that are not available in edge, only in groovy)
However, there is an issue with condition view for multiswitch devices that does not allow unselecting the first switch. Please see [ST Edge] Issue with automation actions for multicomponent switches for details.
Not only child devices are not supported, but it is also not possible to simulate this behaviour with automation.
This is really unfortunate and frustrating