We studied kinetic pathways of order-order transitions in bilayer lipid mixtures using a time-dependent Ginzburg-Landau (TDGL) approach. During the stripe-to-hexagonal phase transition in an incompressible two-component system, the stripe phase first develops a pearl-like instability along the phase boundaries, which grows and drives the stripes to break up into droplets that arrange into a hexagonal pattern. These dynamic features are consistent with recent experimental observations. During the disorder-to-hexagonal phase transition in an incompressible three-component system, the disordered state first passes through a transient stripelike structure, which eventually breaks up into a hexagonal droplet phase. Our results suggest experiments with synthetic vesicles where the stripelike patterns could be observed.