AD9913 frequency sweeping query

Hello,

When performing a ramp up frequency sweep with the AD9913 the sweep will always begin with the auxiliary accumulator initialized with the start frequency (S0).  Similarly, a ramp down sweep will always begin with the auxiliary accumulator initialized with the end frequency (E0).

Is there some way to initialize the auxiliary accumulator with a frequency between the start and end frequencies (S0 and E0) of the sweep?  This would be useful when generating chirps such as would be used with LoRa modulation.

Any help would be much appreciated,

Tim M.