Basically, no. Acid-base reactions occur in aqueous solution, not in the melt, generally. Bicarbonate is likely not stable at stearic acid melting point and will decompose. If you bungle blindly, you're very likely to get a mess. What you could do is is react with NaOH, to form soap. At first, very little will react, you may use alcohol to dissolve some of the steaic acid, so it can mix with the water and NaOH and react. Then, as soap forms, it will dissolve more and more of the stearic acid. I don't know if sodium stearate has the properties you need, however.