On the qualities of Efford, 25, who arrives for an undisclosed fee, ’Well boss Graham Alexander said: “He has a great work ethic, real pace and goal scoring abilities from either side of the front three.
“He’s at a great age and after speaking with him, I know he is highly motivated to succeed at Motherwell.”
Nirennold, 30, is predominantly a right sided defender who most recently played in the Malaysian Super League.
The 6ft 4’ ace, who can also play centre back or right midfield, is well known to Alexander, who signed him in 2015 when the current ’Well gaffer was manager of Fleetwood Town.
Alexander said: “He has attributes that will fit in to how we play, and a character that his team-mates will appreciate. We’re happy to have him here with us and look forward to working with him again.”
Meanwhile, ’Well central defender Darragh O’Connor has joined Queen of the South on loan until the end of the season.
And ’Well defender Rickie Lamie has signed a pre-contract deal with Premiership rivals Dundee.
Dee had an offer to sign the 28-year-old former Livingston centre back this month rejected on Monday, of which ’Well assistant boss Chris Lucketti said: “There has been a bid that’s come in but it’s not an offer that we would accept for Ricki Lamie.
“It’s nowhere near our valuation.”