The SNP's national executive is to meet to decide selection procedures for the snap general election in June.
The party's 54 sitting MPs are expected to be endorsed as candidates.
Labour's executive is also expected to decide candidate selection, while some challengers have come forward for the Conservatives and Lib Dems already.
The UK goes to the polls on 8 June after Prime Minister Theresa May announced plans for a snap election, subsequently endorsed by MPs by 552 votes to 13.
Ms McGarry and Ms Thomson were the only two Scottish MPs to vote against the election, with SNP members abstaining.
If they do not return, the SNP will need to find five candidates, including three for the seats the party did not win in 2015. A number of party activists have already announced their intention to bid for the SNP ticket in the Glasgow East and Edinburgh West seats formerly occupied by the two women.
On Friday, the UK Labour party issued a call for prospective for parliamentary candidates over Twitter, inviting party members to apply with a deadline of noon on Sunday.
The Scottish party's executive group is meeting over the weekend to agree their selection procedure, with leader Kezia Dugdale saying they were ready and had already been preparing for an election.
The party's sole MP north of the border, Ian Murray, launched his campaign to defend Edinburgh South on Friday. Scottish Secretary David Mundell then followed suit in Dumfriesshire, Clydesdale and Tweeddale.
Representatives of other parties have started to declare their candidacies for various seats.
Tory MSP Douglas Ross, who was elected to Holyrood in 2016, has announced he will challenge SNP depute leader Angus Robertson in Moray.
And former Lib Dem MP Jo Swinson said she would seek a rematch with John Nicolson in East Dunbartonshire, two years after the SNP member ousted her from the seat.
The Lib Dems are operating all-female shortlists in a number of target seats, some of which - Edinburgh West included - may be decided over the weekend.