Twenty-nine-year old midfielder Mulley has signed on a permanent deal from National League side Maidenhead United after being on loan at Bostik League Premier outfit Wingate & Finchley.
Part of the Magpies title-winning squad, Mulley brings a lot of experience from this level, after making ninety appearances for the Magpies and then over 100 with his previous club, Braintree Town.
He has also had spells at AFC Wimbledon and Hayes & Yeading United.
Twenty-five-year-old striker Jeffers has signed on loan from another National League side, Boreham Wood, until the end of the season.
Last season, he scored 21 times for Chelmsford City in the National League South, so he's familiar with the task ahead.
Jeffers came through the Coventry City youth system and made half-a-dozen first-team appearances for the Sky Blues in League One.
He has also appeared for Peterborough United, Newport County and Yeovil Town before he made his move to the Clarets in 2016.
Back in 2010/11, he also made two appearances for the England under-19 team.
Both should be available for tomorrow's game at Chippenham Town.