Millions of short period binaries in our Galaxy will be observed by the future space-based Gravitational wave (GW) detector, eLISA. It is expected that thousands of these binaries will be individually resolved for which we can measure their GW parameters. From GW observations we expect to measure their GW frequencies to nano-Hertz accuracies. However most other parameters greatly vary in their accuracies owing to signal strengths and the relative geometry of the detector with the source. I will address to what extent will combining the GW observations (for systems mostly made of white-dwarfs) with their potential electro-magnetic (EM) data can improve our knowledge of the binary parameters further. I will also address the issue of measuring tidal deviations in detached short-period binaries using both GW and EM observations.