Significant changes are being made to the Black Cats' squad following relegation to League One, and it has left new boss Jack Ross short in a couple of positions.
However, Donald has indicated that a lot of work is going on behind the scenes to add another half-a-dozen players before their opening fixture with Charlton Athletic.
Donald is quoted by the Sunderland Echo as saying: "I'm looking at three strikers, at least one midfielder and two centre-halves. Everyone else is two, one and two and I'm three, one and two, so I imagine it will be somewhere between that.
"I've said I'd like three in for Saturday and three in for net week as you want to start getting them into the team as when you play Charlton, you may have decent players but they won't have played together and you want to hit the ground running."