Writing off debt one of your companies owes to another would improve the balance sheet of one and worsen the balance sheet of the other - that could have an impact on all sorts of financial measurements or loan covenants, Not to mention tax reasons - Reading FC only pay tax on profits, If all surplus cash goes on loan repayments or interest then they avoid paying corporation tax. You also get tax relief on interest payments - I think there are some changes due to come into place on that soon.Nameless If the debt was to them then they could just write it off, like Abrahamovic and Fernandes have done and the Bolton guy has said he will do.
The accountants will take all of this into account and recommend the best course of action for their employers - they can then weight that up against the FFP rules.