Dunbar, 28, played club rugby previously for Selkirk as he was making his way through the ranks but has not appeared at this level for a while. However, two weeks after playing for Scotland against Argentina he has been released by Glasgow Warriors for this Millbrae clash.
Robert Kay and Charlie Simpson start in the back division for Heriot’s while, in the pack, skipper Iain Wilson returns. This means Cameron Lineen, Scott King and Struan Dewar miss out.
At Myreside there is an intriguing meeting between fifth-placed Watsonians and sixth-placed Boroughmuir.
Both sides know a positive result is needed to keep up the pressure on the top four and the play-off spots and Watsonians have lock Jamie Hodgson back after Edinburgh duties. Ross Graham moves from hooker to back-row meaning Fraser Renwick starts in the front-row.
Craig Gossman and Rory Arthur are back to inject some real pace into the Boroughmuir back three, while Edinburgh’s Fijian Senitiki Nayalo is in the back row.
Second-placed Melrose are in the capital to play bottom-of-the-table Edinburgh Accies.
Craig Jackson is fully recovered from injury and starts at 12 for the visitors outside Edinburgh’s Jason Baggott at stand-off.
Jamie Loomes is given the No 10 jersey for Accies with Scotland cap Murray McCallum at tighthead prop.
Currie Chieftains have four pro players in their 20-man squad for the home match with Stirling County, among them Kiran McDonald starting in the second-row.
Andrew Goudie is back at ten for County.
Glasgow Hawks host Hawick with Grant Stewart back at hooker. The Greens have Daniel Suddon returning in the second-row.