The limit is 10 DCS engines.
From The DCS Companion 3rd Edition page 103 and The DCS Wifi Companion 1st Edition page 89:
Up to 10 DCS engines can be members of a lashup. Regardless of how many DCS engines are included in the lashup, one engine will always be the head engine, another will be the tail engine and up to 8 additional engines as power in the tracks can support may be designated as middle engines. A DCS engine may be the member of more than one lashup, however, only one of the lashups of which it is a member may be operated at the same time. Each lashup will have a unique DCS engine ID#.
 | This and a whole lot more about DCS is all in MTH’s “The DCS Companion 3rd Edition!" This book is available from many fine OGR advertisers and forum sponsors, or as an eBook or a printed book at MTH's web store! |
 | This and a whole lot more about DCS WiFi is all in MTH’s “The DCS WiFi Companion 1st Edition!" Get the free TMCC & Legacy Addendum here! |
