Q. If five people already davened and five need to daven, may one of those that already davened say a tefillas nedava so that there will be six mispallelim? May this be done in a case of need, such as where they will be very hurt by not having tefilla b'tzibbur?
A. Horav Shlomo Miller’s Shlit’a opinion is that davening a voluntary Tefila, would not create a communal Tefila Betzibur. Besides, the Rov pointed out that it is not recommended to daven in our days a Tefilas Nedava, since it requires kavana and complete intention in all the brochos, and that is difficult to achieve in our times.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit'a