Pompey have extended the loan deals of Ross McCrorie and Cameron McGeehan.
It means that both players will be available to compete for the Blues in the League One play-offs next month.
Scotland under-21 international McCrorie arrived from Rangers last summer and has made 22 appearances, being utilised in both a full-back and midfield role.
McGeehan was borrowed from Barnsley in January and has struck twice in 15 outings, with crucial goals in Leasing.com Trophy wins over Scunthorpe and Exeter.
Kenny Jackett had already secured an extension to Steve Seddon’s loan deal from Birmingham to cover the play-offs.
Pompey would like to thank Barnsley, Birmingham and Rangers for ensuring all three players are able to complete the season at Fratton Park.