A modular system of devices, in which a (master) device can be combined with one or more of other (slave) devices to transform to functional electronic devices having expanded functionalities and features in different form factors and/or platforms. The master device is docked to the slave device via a data/electrical interface, to transform the master device to the larger form factor of the slave device, with the master device maintaining control of the slave device, substantially based on the operating system installed in the master device, with access to the data, application programs, functionalities and features embodied in the master device. An intermediate removable physical interface adaptor (or docking adaptor) is provided to facilitate docking compatibility of the master device to the slave device. An enhanced charging and power management scheme is provided to optimize power management for the master device and the slave device.