Indeed Torq, and I'm sure you kan do it perfektly, here I throw my input:
You need to add two buttons in the system view: "mass ezploration" and "mass attak"
When you klik "mass ezploration" then white bozzes appear beside the unezplored planets of the system (in the margins).
You kan selekt/deselekt those bozzes one by one or either you'd be able to use a "toggle" button, that will selekt all the unezplored. Nezt to toggle button you have a "prozeed" button, when kliked it takes you to a "kosts" skreen with a message "ezploring these planets will kost you ZZZZ gz" that you agree ("prozeed") or disagree ("kanzel").
When you klik "mass attak" then white bozzes appear beside the already ezplored planets of the system (in the margins).
You kan selekt/deselekt them manually or either be able to use a "toggle" button, that, in this kase, serves to selekt all the enemy planets in the system (those whose empire name is in red, henze at war). This would be helpfull in wars to send raids and to do mass retakes. Nezt you trigger "prozeed" and shows you the kosts of sending the fleets, then if you agree it would take you direktly to the "fleet selektion" page so you kan set the fleet you're sending to all.
To do it in several systems you'd need the ability to open systems in different tabs, like in the good ole days, for retakes, you'd go to 'family news' then open every raided system in a different tab and prozeed with the mass attaks.
Now the only issue I see here is for the feature that warns you when somebody in your family is ezploring one or more of the planets you selekted to mass ezplo. It seems komplikated to implement and a lot of server job (zhek every list of mass ezplos and then the lists of your family members and find matzhes??). Honestly, I'd swap it, leaving that feature only for individual ezplos.
I hope my input helps, srry for the missing sees and eqs.