A number of Belfast grammar schools are set to increase the number of pupils they can admit in 2020.
The Education Authority has published a development proposal which would allow Strathearn to grow pupil numbers.
There are also plans for three Catholic grammar schools in Belfast to permanently increase enrolments.
According to the EA, a full set of proposals for adjustments to pupil numbers in a range of Belfast schools will be brought forward in January.
"Due to a growing demand for post-primary places in Belfast many schools, non-selective and selective, are experiencing increasing pressures from parents and the local community to make more places available," said the EA development proposal.
"The proposal for Strathearn School is being brought forward in advance of the full suite of proposals."
Strathearn School is a girls' grammar in east Belfast which currently has 770 pupils.
Under the new proposals pupil numbers at the school would eventually rise to 840.
That would mean that Strathearn could admit 120 pupils in September 2020 rather than the current 110.
There are also proposals to allow Our Lady and St Patrick's College Knock, St Malachy's College and Aquinas Diocesan Grammar School to increase pupil numbers.
Aquinas Diocesan Grammar School plans to increase numbers from 770 to 910, admitting 130 new pupils every year as a result instead of 110.
Our Lady and St Patrick's College plans to grow to 1,330 pupils from 1,260 at present, and admit 190 pupils a year instead of 180.
Consultations to take place
St Malachy's College, meanwhile, has proposed enrolling 170 new pupils a year rather than 150 and increasing its total numbers by 140 to 1,190 pupils.
Assumption Grammar School in Ballynahinch, County Down, also plans to increase its enrolment from 840 pupils to 910.
Consultations on the proposals will now take place.
The only Irish medium post-primary in Belfast - Coláiste Feirste - also recently announced plans to increase its pupil numbers by 50%.
The number of pupils transferring from primary to post-primary schools has been growing in recent years, putting pressure on places in some areas.
The Department of Education (DE) had previously announced temporary extra places for a number of schools in March 2019.