That is not the idea, An 'open invitation' with priority should mean that
if (and only if) the prioritary person rejects the invitation, then the
invitation can be considered open. O.K., this is equivalent to extend a
new invitation, only there is some extra work, so no more discussion on
this topic for the moment.
Deleting logs?. I think it should be done in an easiest way... But I am
not very critic about this, PBM system, as concept, is great; many
improvements may come in the future, surely.