Imran,
To drag all children? in the Object Manager or View? In the Object manager, Set Parent. However, it destroys any hierarchy that was given to any of the selected objects.
MMB perhaps? But that is for the Object Manager.
If an element needs a lot of tweaking, while being in a cluster of objects, it is common practice to provide handles (Character Animation would be the main example here). If that is not your target, then don’t use it. If something is a good or bad idea depends on the context and other things.
In the first post, you wanted something that different than you describe in the last post of yours.
I’m not aware of a default hotkey for “click and drag all child objects”.
A Selection Object can be created to define a group and single objects in a mix to be selected at one.
In the Main Menu> Window> Customization> Customize Commands, you will find all possible commands and shortcuts. Search for Child, Parent, Object, Move, etc.
Besides that, you can use the Script log and create a new script, which can have then in return its own Hot-Key
Another way is to have a Selection Filter supporting your work. Which can be “recorded” with the script log and with individual hotkeys, you might shape the tools you need.
Perhaps make a suggestion:
https://www.maxon.net/en-us/support/suggestions/
Your questions seems to turn directions with each post, I can interpret them in too many ways. Please describe it with a scene file attached. Let me know if there is anything else, I’m happy to look into it.
Cheers
P.S.:
Is this what you are looking for?
https://www.cineversity.com/forums/viewthread/1307/