Absolutely! Shared Pockets have the Pocket Protector option. Only the Pocket owner can turn on this feature since funds will always be pulled from the Pocket owner's Spend Pocket.
For example, let's say Marisa is the owner of a Vacation Pocket and shares it with Alex. Marisa will have the option in their One app to turn on Pocket Protector for their Vacation Pocket. Alex will not see the same option.
Now let's imagine Marisa has Pocket Protector turned on for their Vacation Pocket which currently has $500. Alex finds flights for $560 and uses the Vacation Pocket to make the purchase. Since Marisa is the Pocket owner, the $60 needed to complete the purchase will be transferred from their Spend Pocket even though Alex is making the purchase.