Unlink_parameter() method makes the parameter completely local, so it will be fit only to its own dataset. This may be done after a fitting session with global fitting is performed as a way to obtain a starting value for this (now) local parameter. Alternative way to do it is to generate a new TotalFit object with different linkage between parameters and simply reassigning best-fit values in the former object to initial values in the latter one.
IMPORTANT NOTE: After linking/unlinking operations are done one have to regenerate the total vector of parameters and lookup vectors (the fitting environment). (see below in GENERATING ALL-PARAMETER AND LOOKUP VECTORS)
For a specific usage see TotalFit.m