While Microsoft has yet to confirm this addition, a couple of members of the Windows Central forums have posted word they have managed to download and install the most recent Insider build of Windows 10 Mobile, version 14328 that was released on Friday to the Fast Ring.
Another report from WindowsArea.de claims that the earlier BLU Win HD model is also supporting the new Windows 10 Mobile Insider Preview build, but we have yet to confirm that news. Hopefully, Microsoft will issue an update on their list of Insider phones shortly.
In the past, some phones have accidently gotten by Microsoft's prescribed list of phones for the Insider program, so we are not sure if this is a genuine change or a fluke at this time.
Currently, BLU accounts for 0.24% of all Windows Phone active on the market according to data from AdDuplex.