This should be possible without any further equipment, especially if the Minilogue is your MIDI keyboard.
In brief:
Physical connections:
Minilogue MIDI Out to Digitakt MIDI In.
Digitakt MIDI Out to Digitone MIDI In.
Digitone MIDI Thru to TX7 MIDI In.
TX7 MIDI Thru to Minilogue MIDI In.
Settings:
Set Minilogue to ‘Local Off’.
Set Minilogue MIDI channel to match Digitakt’s Auto channel number.
Set Digitakt’s MIDI tracks channel numbers to match the channel numbers of the synths; for the Digitone, use its autochannel number.
When you select the appropriate MIDI track on the DT, the Minilogue can control whichever synth is set on that track.