Sure, you can add a buffer, if you pipe it in series, it just becomes an addition to the OWB capacity. keep in mind it will see O2 and rust away if it is a plain steel vessel. Add O2 scavenger chemicals from time to time available from the OWF dealers. Is the distribution a pressurized loop? If so you need a heat exchanger in the mix, shown on page 20, for example.
https://www.caleffi.com/sites/default/files/file/idronics_10.pdf