Post the model.
the problem is you have a combination of a profile with no sharp corners and a profile with four sharp corners. You can't add fillets to your final result because one profile has no breaks in tangency and you can't eliminate the sharps because your other profile has four singularities.
What you'll need to do is either remove the rounds from your pan-handle profile or add rounds to the corners of the profile on the cylindrical body.
In this specific case, you probably need to do the latter using split lines to define wher eyou want your blends to land on the main body, like this:
I uploaded the model if you want to see how I set it up.
boundary_srf_blending.SLDPRT.zip 162.2 KB
Are you worried about the part cracking, or are you worried about the mold that will make the part cracking? Sharp internal corners cause stress concentrations, so the mold for your part might crack. Sharp external corners don't cause stress concentrations, so your part should be safe from that concern.