Dunstable lost more ground in the hunt for the top two in the Saracens Herts League Championship after a rain affected draw against Chorleywood on Saturday.
Ben Welch smashed a 30-ball 49 as Dunstable reached 196-8 from 41 overs, whilst James Bromhall scored 41 after 27 from Ben Abbott.
Luke Cherry claimed 4-36 in return but Dunstable could only take seven wickets as the hosts reached 146-7.
Sam Marshall snared 4-28 as the IIs picked up their fourth victory in five weeks.
Marshall took four wickets after Harry McBrearty claimed 3-18 to bowl North Mymms IIs out for just 92.
Dunstable lost a wicket early on but Mark Smith hit a 56-ball unbeaten 50 and Richard Kilduff finished 35 not out as the hosts claimed a convincing nine-wicket victory.
Marcus Connor claimed 5-5 as the IIIs bowled Stevenage IIIs out for just 114 at Lancot Park.
He also hit 38 with the bat whilst Ian Horton scored 79 and Shoaib Rashid 36 not out as Dunstable posted 219-7 from 48 overs.
Chris Pell then took 2-37 as Dunstable claimed a 105-run victory.
The IVs were beaten comfortably by Risely after being bowled out for just 75.
George Whitcombe took 3-18 whilst Joe Moss and Harry Griffin managed two wickets apiece.
The hosts had scored 165-9 before Dunstable were all out in 33 overs.
The Sunday first team proved just too strong for Langford winning their Bed County League Premier Division clash by two wickets
After the visitors made 170, Dunstable reached their target at 171-8.
The IIs kept up the pressure on Eggington at the top of the Second Division with a narrow win over Blunham.
Dunstable were set 166 to win after Harry Wright took 3-31 and Tarnjit Biryah returned 4-9. Ian Horton (38) and Andy Boocock (32) shared an opening stand of 66 and Ryan Connor’s 27 meant Dunstable reached 168-8 with just five balls to spare.
The IIIs had to concede due to a lack of players.