The players will continue their development at the club with both the first team and under-19 squads initially.
Macdonald, a right back and McQuillan a left sided attacker, have extended their stay with the club for another year.
Women’s and Girls Football Manager Amy McDonald said: “We’re delighted that both Rosie and Freya have agreed to stay with the club for another year.
“Freya has already shown that she is capable of stepping up when required and we are keen to help her continue her development at the club.
Both players have first team experiences already and are established youth internationals, with Freya having been capped seven times for Scotland under-17s and Rosie having represented Scotland at under-15, under-16 and under-17 level, where she’s scored six goals in 12 matches.