A network node (110), a first device (111) and methods therein for managing a HARQ parameter indicating a number of autonomous HARQ transmission attempts to be applied for a transmission on at least one D2D link between the first device (111) and the second device (112) are disclosed. The method comprises determining (A010) a load relating to D2D communication between at least the first and second devices (111, 112). Next, the HARQ parameter is determined (A020) based on the load. Corresponding computer programs and carriers therefor are also disclosed.