The issue can be resolved as follows:
1- Calculate the point load (P, the transfer load) from the upper levels using the tributary area method (you can use the TribKALC online software).
2 - Assume your transfer slab spans a 6x7 column grid, with end spans on each side (i.e., fixed-pin support conditions).
3- The moment in the long direction would be:
M = P × Long Span / 6 / (0.65 × Short Span)
Note that the "6" in the denominator accounts for the fixed-pin support condition. If you have pin-pin supports, you would divide by 4 instead.
This gives the moment per unit width of the slab. Use this value to calculate M/bd². If the result is, say, less than or equal to 2, then the strength is satisfactory.
4- Deflection can be calculated using the formula:
Δ = M × L² / (13 × EI) for pin-fix supports (and "13" can be replaced with "10" for pin-pin supports).
5- Similarly, calculate the moment in the short direction as described in step 3, to get an overall understanding.