Scotland women: Signeul hopes to add Barsley and Howard to squad to face Belgium
Vaila Barsley and Sophie Howard, both previously involved with England, are poised to be drafted into a Scotland squad badly hit by injuries.
But Arsenal full-back Emma Mitchell could miss this summer's Euro 2017 finals after undergoing surgery.
Celtic 22-year-old Kelly Clark has been named in the squad for the first time for the 11 April friendly with Belgium.
Fellow central defenders Barsley, 29, of Eskilstuna United, and Howard, 23, of Hoffenheim, await paperwork.
Head coach Anna Signeul had hoped to announce their call-up on Wednesday but expects international clearance to arrive in time for them to be added to the squad for the match at Stadion Den Dreef in Leuven.
"They are very excited, but it is also really frustrating," Signeul, who will be without central defenders Jennifer Beattie, Rachel Corsie and Joelle Murray through injury, told BBC Scotland.
"The reason they have not been selected before is that I think we have had four very good central defenders in Scotland - Ifeoma Dieke, Jennifer, Rachel and Joelle.
"But three of them are not available and this is a great chance for Vaila and Sophie - and also for Kelly Clark, who is doing really well at Celtic."
Born in England, Barsley qualifies through her mum, who is from Shetland, while Howard was born in Germany but has a Scottish grandfather.
Barsley was a youth with Norwich City and Arsenal and played at under-17 level for England.
She had spells with clubs in the United States, Iceland and Ireland before moving to Sweden's top flight in 2013, where she plays alongside Scotland striker Fiona Brown.
Howard, who also played in the United States before joining her present Bundesliga club in 2015, has turned out for Germany at under-20 level and was in the England Next Gen squad last year.
Injuries to Arsenal midfielder Kim Little, Glasgow City pair Hayley Lauder and Jo Love and Hibernian defender Rachel McLauchlan also contributed to Signeul only being able to name 19 players in her squad.
Chelsea midfielder Erin Cuthbert will also miss out because she is playing for Scotland Under-19s in elite round matches against Republic of Ireland, Finland and Ukraine.
The coach will therefore invite potential additions to the squad to a pre-game training camp before they leave for Belgium, with the intention of bringing the travelling party up to 23.
Signeul said that all the injuries apart from Mitchell's were "precautionary" and therefore short-term, but she expressed concern about the Arsenal player's chances of making the Euro finals, being held in the Netherlands in July.
"They say three-to-four months, so it can be touch and go," she said of the 24-year-old.
"We are still hoping. That would be massive to lose her."
The spate of injuries will give Glasgow City goalkeeper Lee Alexander and Hibernian midfielder Lucy Graham, who have both been in previous squads, hope of earning their Scotland debuts.
Belgium, who have won two and lost two in previous meetings with the Scots, have climbed to 23 in the world rankings - two behind April's opponents - and Signeul views them as one of the best up-and-coming sides.
"We have played them before and they are always very tough," she said. "They have always had individually skilful players, but now they are getting it together as a team as well."
Meanwhile, Signeul is hopeful of finding grass venues for forthcoming home friendlies against Romania and Ireland - the other being away to Sweden - as they prepare for the finals.
"Last year, we had to play our home qualifier against Iceland on Astroturf and I don't think that was to our advantage," she added.
Goalkeepers: Gemma Fay, Lee Alexander (both Glasgow City), Shannon Lynn (Vittsjo GIK)
Defenders: Frankie Brown (Bristol City), Kelly Clark (Celtic), Ifeoma Dieke (Vittsjo GIK), Nicola Docherty (Glasgow City), Kirsty Smith (Hibernian)
Midfielders: Leanne Crichton (Notts County), Claire Emslie (Bristol City), Lisa Evans (Bayern Munich), Lucy Graham (Hibernian), Christie Murray (Doncaster Rovers Belles), Leanne Ross (Glasgow City), Caroline Weir (Liverpool)
Forwards: Lizzie Arnot (Hibernian), Fiona Brown (Eskilstuna United), Lana Clelland (UPC Tavagnacco), Jane Ross (Manchester City)