The fee is already set at £6m (rising to £7m) for Defoe with Zamora going the other way.
Given that is the case, what I am saying is that it is in both club's interest to say that Defoe is worth the entire value of the transfer fee rather than say £11m for Defoe and £5m for Zamora.
Otherwise...
That doesn't make sense. Either they're both valued highly or they're both values lowly. Either way, there's a £6/7m difference in their valuation. It's actually in both clubs interest to value BZ as a free transfer and Defoe as the rest, but they won't get away with that.