Hi zorojan,
Welcome to the SEBLOD forums.
One idea, In the search type for the Offers, you could have a field that shows a link (ID) only available for the "Job" user. The link would then open the Offer form to Edit.
In Edit Mode, perhaps a checkbox field for Accepted - available to Job User. Upon Checking could then enable an Email Field, and enable/visible FreeText field using Conditional States (option #5). The FreeText field could have "Offer Accepted". Then upon submission of the form, it could send out an email to the parties.
Is that what you are thinking?
Randy