Thor has pretty much always beaten Enchantress and Skruge together, even when disoriented, so lady sif isnt necessary.
Journey into the Mystery 103 (1952) : Well first Thor vs Enchantress and Skruge Fight , Thor won handily
The Mighty Thor 403( 1989) : Thor wins again, he is disoriented to being with thanks to the action of Quicksand, and still manages to beat Skruge handily
The Mighty Thor 17 (2012): Thor beats them both
What i am trying to get at is, neither Skruge, nor enchantress nor both of them together have power to actually take down Thor, unless he is being jobbed and this does not change even if you look way back at classic days, towards middle of his history, or the most recent issues.
While the first encounter i posted is BFR, Thor could just as easily used winds of 1000s worlds to outright kill them, its just he opted for a subtle approach.
I do not think Lady Sif is needed, fighting the way he should, Thor would win against these two ever since time by himself, be it with or without morals.