It is understood that visa problems resulted in a New Zealander being forced to fly straight back home after arriving in Edinburgh to take up the reins at Bangholm.
For tomorrow's home Scottish regional bowl clash with Portobello club stalwarts Robin Hamilton and George Rendall will continue to fill in with senior players also helping out at training.
A club official confirmed Trinity were actively back in the market after previous plans ran into red tape difficulties.
Meanwhile, Boroughmuir are set to give a recent Scotland under-18 cap a baptism of fire in Premiership A tonight when Heriot's are entertained at Meggetland (7.30pm).
Second row Will Kay gets his chance in the squad as a consequence of injury to former Dunfermline lock Tom McColl although ex-Edinburgh pro Ally Davidson is available again in that position after a recent absence.
Kay is credited with some outstanding performances at second-team level and manager Ally McLean said: "Will is a tall, rangy lad who has come up through the ranks to earn his chance.
"He is quick about the pitch and one of a number of promising youngsters around the club."
The priority for 'Muir is arresting a run of three league defeats broken by a cup victory over Dalziel. Memories of a 24-20 defeat by Heriot's last month are also still vivid and McLean commented: "Heriot's just deserved to edge a match that taught us a lesson about needing to be a bit more clinical in our finishing.
"Having the likes of Ally Davidson back should certainly help because somebody of his experience inevitably gives a strong lead to our younger lads."
Injury problems mean 'Muir have had to delay finalising their threequarter line while Heriot's team plans are unavailable.
Title-chasing Currie have received a boost with the return of Scotland under-18 hooker Fergus Scott for tonight's vital clash at Glasgow Hawks.
Scott's return to understudy Stuart Simonsen is particularly timely with Finlay Gillies required by Edinburgh while James Johnstone has been withdrawn to prepare for upcoming Scotland sevens commitments.
Hawks saw their title hopes dented by Ayr last week but Currie coach Ally Donaldson is wary of a backlash, saying: "Hawks are very strong all round and have played some good rugby this season."
Hawks counterpart Peter Wright says:
"It was a bad result last week but we had our chances."
Wright retains the same back line but has Adrian Smith and George Hunter starting at prop instead of Gary Strain and Ryan Grant.
In group B Edinburgh Accies head for Stirling County fresh from avenging their only defeat so far this season, against a Peebles side who now entertain Watsonians.
Stewart's Melville are at Kirkcaldy.