The manager said: "I have spoken to two clubs, including Wigan, about players I am interested in but I have to be patient, because injuries, suspensions and International calls make Clubs reluctant to let them out.
"The boot is on the other foot now because that is how I was about now because that is how I was about requests for my players leading up to the transfer window and Cup games."
Michael Brown is a target for the Bramall Lane club and Blackwell admits that the Wigan Gaffer Steve Bruce has been honest. Blackwell continued: "Steve Bruce has been brilliant with us, very honest and up front about his situation. He has injuries and suspensions so Michael Brown is part of his squad, and that is the situation with one or two others elsewhere.
"But I am not looking at Premiership reserve players who will never figure, I am looking at targets who are in the squads and could make an impact for us.
"I have to be patient, as we were when Michael Brown was eventually signed here. It took weeks but he took us to another level because he was the right one and it was worth the wait."
In the transfer window Blackwell indicated that he is a fan of former Plymouth Argyle midfielder Peter Halmosi. Blackwell finished:
"He is not in the side at the moment but Phil Brown needs a squad to survive in the Premiership, and most players need time to settle in. We still have Darius Henderson, Matthew Spring and Sun Jihai out of suitcases so we can expect more to come from them."