A feature which has been available in the Android version of the WhatsApp app has finally arrived on Windows Phone.
Version 2.17.176 of the WhatsApp Beta now lets you pin contacts to the top of your contact list for easy access. Up to 3 contacts can be pinned.
Despite good support by Facebook the future of the WhatsApp for Windows Phone is somewhat unclear, as recent leaks suggest Silverlight apps such as the WhatsApp app will not be supported in future versions of Windows 10 Mobile, and given the small user base, it seems unlikely Facebook will invest in a new UWP app.
In the mean time, you can download WhatsApp beta from the Windows Store from the Store link below.