  Based on results from cold dark matter N-body simulations we develop a
dynamical model for the evolution of subhaloes within host haloes of galaxy
groups. Only subhaloes more massive than 5 times 10^8 M_{sol} at the time of
accretion are examined because they are massive enough to possibly host
luminous galaxies. As they orbit within a growing host potential the subhaloes
are subject to tidal stripping and dynamical friction. We consider groups of
equal mass (M_{vir} = 3.9 times 10^{13} M_{sol}) at redshift z=0 but with
different concentrations associated with different formation times. We
investigate the variation of subhaloe (or satellite galaxy) velocity dispersion
with host concentration and/or formation time. In agreement with the Jeans
equation the velocity dispersion of subhaloes increases with the host
concentration. Between concentrations ~5 and ~20 the subhaloe velocity
dispersions increase by ~25 per cent. By applying a simplified tidal disruption
criterion, i.e. rejection of all subhaloes with a tidal truncation radius below
3 kpc at z=0, the central velocity dispersion of 'surviving' subhaloes
increases substantially for all concentrations. The enhanced central velocity
dispersion among surviving subhaloes is caused by a lack of slow tangential
motions. Additionally, we present a fitting formula for the velocity anisotropy
parameter \beta(r) which does not depend on concentration if the group-centric
distances are scaled by r_s, the characteristic radius of the NFW-profile.
