Request: Raiding Chest Lock Party Finder Option

[Kaldaka]

I'm making this post, purely because six people just got seriously shafted by two unknown players in the party I made. The six of us, oblivious to the two people lurking who had already cleared OS5 for the week, thus rendering us with only a single chest. (I did not see any messages upon entry - lesson learned).
We were asked each time people joined the party "Two chests?" we would answer "Yes". This happened several times. However, it's pretty damn malicious of people to join KNOWINGLY screwing the rest of the party over on the drops.

Request:
It doesn't need an additional button, but a tweaking of a pre-existing button. For example the "Loot" selection could be adjusted for the Savage portion of party finder to lock in max number of chests.
In opposition, "Duty Completion" could be adjusted to where it's not about the chests, but essentially just the book from completing.
These tags are both descriptive, so why not put them to proper use to?
OR, as Taika (post below) has mentioned: If the above is infeasible, make it so that the whole party is aware of the warning notice upon entry, not just a single player.

Please consider the request for change as it only takes one person to screw over an entire party, surely preventative measures can be put in place? Peoples word isn't worth much nowadays.
This happens all the time, we six are not in the boat alone, however this doesn't need to be the case.

(PS: I am aware of the raid finder options, however, the lock should be under party finder to prevent time wasters from even joining the party in the first place).