The Davison Chart is calculated from an actual time and place ...[ie. the mid-points of the time/place of the two individual natal charts]...
This means that it is (technically) no different from any other natal chart, Kbell ...So it can be progressed in the same way as a natal chart ...(and/or used to calculate Solar/Saturn/Other Return Charts, or anything else that is derived from natal charts).
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Note : We cannot progress Composite Charts in the same way as natal charts...
because they are based on the mid-points of the planets in the two individual charts, which are not necessarily progressing at the same speed ...[For example, Mercury might be retrograde in one natal chart but direct in the other ...so their mid-point would not progress "normally"]...
Consequently ...(as Wintersprite1 explained to me on another thread) ...Composite Charts are progressed by first progressing the two individual charts, and then using their mid-points to produce a new (progressed) Composite Chart.
EJ