The disclosure relates to the field of holding frames for a plug connector for receiving similar and/or different modules. To provide a way of populating a holding frame with modules even when the holding frame is already installed in a casing, and in a manner that is compatible with known modules, a holding frame arrangement for a plug connector for receiving similar and/or different modules is proposed, comprising a base frame adapted to receive a module and a fixing element adapted for fixing to the base frame such that the base frame and the fixing element fixed to it together define a fixing window for engaging a fixing lug of a received in order to fix the module in place.