Using the read-across or trend analysis functions, you can only fill data gaps one by one. But you can save your category as a QSAR model and then apply your model to the data matrix. Once you have saved the model it will appear in the list of (Q)SAR models in the module "Data Gap Filling". Right-click on it and select Predict/Predict chemicals in domain. That will calculate all loaded chemicals for which the QSAR applies. As the applicability domain of your model will be small, don't use Predict/Predict all chemicals as this will be meanigless for most chemicals.