My understanding is that this is an evidentiary hearing in which the defense (for the Trump side) is gathering testimonial evidence from witnesses to establish that, either or both, a crime was committed by Fani (and Wade) and/or Fani's romantic involvement with Wade had a prejudicial effect on the case against Trump.
At this point, it looks like Ashleigh Merchant and team are trying to establish, at the least, that the relationship between Fani and Wade started before Wade was hired by the DA's office. Ancillary to that, I think that Merchant et al. are trying to establish that the behavior of Fani and Wade was a financial abuse of the DA's office and Fulton County (trips paid for by Wade for himself and Fani were a form of graft--Fani overpaid Wade and he return the favor with gifts).
As to the question of gifts by vacations, it has been established that Wade paid for all the vacations with a credit card and Fani (it is claimed) reimbursed Wade with cash without any paper trail such as withdrawals of cash by Fani, deposits of cash by Wade, or receipt for such reimbursement (given by Wade to Fani showing amount and reason for an exchange of cash).
As an aside, the DA's office requires Fani to report any gifts and it would appear to be incumbent upon Fani to have a receipt from Wade for her reimbursements for vacations so that she can prove such vacations were not gifts. As it stands right now, Fani has no way of proving that she repaid Wade for her share. In other words, there's no evidence (or paper trail) to show that all those many vacations were not gifts. Fani expects us to take her and Wade's word for it.
Regarding the start of the affair before Wade was hired, Merchant and the defense team already have sworn testimony of a close personal friend of Fani's (who was a former employee of the DA's office).
Ancillary to that, I think that Merchant et al. are trying to establish that the behavior of Fani and Wade was a financial abuse of the DA’s office and Fulton County (trips paid for by Wade for himself and Fani were a form of graft—Fani overpaid Wade and he return the favor with gifts).
IMHO, the question here is that going after Trump represented a scheme to abuse the office in a way in which 680 thousand dollars could be awarded to a “special” counsel of the Fulton County DA’s office. The purpose of calling Barnes this morning was to show an experienced and seasoned counsel was not interested in this endeavor which cuts both ways. It makes the case an experienced lawyer who valued his reputation had NO interest in conducting this sham prosecution. It cuts for the DA in that it gives a reason why such an unqualified a lawyer was awarded the contract. The major point is that prosecuting Trump was the ONLY way in which Fani’s boy toy could EVER be awarded 680k of the taxpayer’s money.