BiQuad DSP filter config with Q15 coefs - how to? (CMSIS-DSP)

How do I configure BiQuad DSP filter using q15 coefs, e.g. calling arm_biquad_cascade_df1_init_q15() method?
I guess, I am missing some basic concepts here. Calculated coefs (e.g. with this calculator) can have values greater that 1 and I do not think I can just scale them down since arm_biquad_cascade_df1_init_q15() method seems to expect standardized values (a0=1). See this picture.
How to correctly convert calculated coefs to q15 values?

With arm_biquad_cascade_df1_init_f32() method it is not a problem since coef are of f32 type but I prefer using q15 version.