The club have also been heavily linked with Norwich midfielder and Scotland worldwide Graham Dorrans, Mexico global Carlos Pena and Benfica duo Daniel Candeias and Dalcio as Caixinha looks to shake up the Gers team.
Rangers targets Eduardo Herrera, Fabio Cardoso and Dalcio are undergoing their respective medicals after arriving in Glasgow.
Cardoso is a former team-mate of Dalcio with Benfica B and also played for the Portugal youth teams – and the 23-year-old is set to line up alongside countryman Bruno Alves, Caixinha’s first signing, in the Rangers central defence.
Meanwhile, Dalcio is expected to conclude a loan deal from Benfica.
The 28-year-old, who attended Saturday’s Champions League final, said: ‘I’m happy to be here’.
Reports in Mexico claim Pena has agreed a three-year deal although Rangers must secure a work permit for the attacking midfielder.
As reported by The Daily Record, Pedro Caixinha is set to add more talent to next season’s Rangers squad with the acquisition of two stars from Portugal.
Jack became Rangers’ second summer signing with Portugal global veteran Bruno Alves announced a day earlier on Wednesday.