Iain Turner, who made a costly mistake in the weekend home loss to Fleetwood, is set to continue to deputise this weekend for Howard, who has been sidelined with a back problem, but is on the mend.
Flynn suffered a hamstring strain late on in the defeat to Peterborough at Bramall Lane eight days ago, while young defender Kennedy (knee) is on the rehabilitation trail, as is midfielder Jason Holt (ankle).
Stefan Scougall (knee ligament) is also making progress and could return to action in an under-21 game shortly, according to Clough, although he will not be rushed back to action after his considerable spell out.
On Howard, Clough, whose side return to action at Scunthorpe United on Saturday said: “He is coming along well, although I am not sure he will be okay for this Saturday, but we are hoping for Tuesday or the Saturday after.”
And on Kennedy and Flynn, Clough said: “Terry is exactly as we thought at this stage and will be a couple more weeks or something like that.
“It’s a four-week injury he did, so it’s two weeks down time and strengthening his knee with weights and hopefully he will be up and running next week with a view towards the end of the month.
“Ryan is doing some work. We are not sure he will be okay for Saturday, but we are hoping so. Although it might be a little bit too soon.”