Allen will combine his existing role as Pompey physio with assistant manager in the new-look set-up.
That has left the door open for Whittingham to bring in a coach to help him on the training ground.
The Blues boss insists he has no immediate timeframe in which to identify his preferred target.
But he has revealed he has already approached several candidates as he seeks to complete his Fratton Park backroom.
He said: ‘A first-team coach is what I am looking for.
‘Somebody who can take on primarily a coaching role.
‘It’s on-going, I have talked to people and there are lots showing interest.
‘But I’m quite relaxed, if it isn’t done by the time training starts on June 27 then it isn’t done by then.
‘It has been far more important to get players in and we have really hammered down that line.
‘We think we have done quite well from that point of view.
‘I probably took my eye off the ball a little bit maybe with a first-team coach.
‘But now I know one is needed and the type of person I want, I am quite confident I will find one.
‘I want somebody with the same desires as we have, the same work ethic and the same morals in life. I think that is very important.
‘I just want somebody who is a good coach, somebody who is enthusiastic, someone who shares the challenge we have got and is determined to see it through.
‘I will continue having discussions with people.
‘But I wouldn’t think it will get sorted before I get back from holiday.
‘I hope in a couple of weeks it might be done.’