I worked in a University in NI
The school have strongly but subtly recommended that the pupils should not go to either UU or QUB, something to do with entry requirements being over inflated because places are capped here but not in the rest of the UK.
Grade boundaries are set so Universities can ensure that the student has the skills to meet the demands of the course they have applied for. After the A-Level results are published we often drop A-Level grades for GB applicants as you have said they aren't capped places but the actual number of GB applicants who gain these places are really low (double figures), and its often only an A-Level grade drop and not for professional courses (i.e. Dentistry, Medicine Social Work ect)
She intends to apply for dentistry (which is QUB only) and apparently 60+% of applicants who meet the grade requirements get rejected because of competition.
Dentistry is a highly competitive course in order to narrow down who is selected for a place all applicants who meet the minimum shortlisting requirement (GCSE Grades for School Leavers) are required to be interviewed.
After interview applicants are ranked (1 - XX (how ever many where interviewed)) and places given 1 - XX (now many spaces are available). Due to the volume of eligible candidates available a Universities don't allow any grade drops for these courses (regardless of your residency status), if someone doesn't meet the grades when the results are published it goes to the next person on the list, again regardless of residency status.
32 places therefore you will need much higher than the 3 A's they state
This is incorrect the grades published online and in the prospects along with the specific subject requirements are what is required. Universities are really transparent on their requirements. There is no hidden agenda.
Your daughters school has given you a lot of incorrect information and I strongly encourage you to contact the Admissions Department for each University your daughter in intending on studying at for further clarification.
As your daughter will need to attend interviews at the other Universities she intends on applying to she could use that as an opportunity to look around the other campus' in my experience they don't often offer Skype but some do provide funding for widening participation students to attend, again query this when your emailing them regarding entry requirements.
Finally congratulations on raising an extremely bright daughter who is in a position to consider dentistry as a career option, please don't be overwhelmed the admissions teams deal with these sorts of queries all the time and are more than happy to help.