Recently,　C30　coefficients　of　time-variable　gravity　field　models　from　GRACE　and　GRACE-Follow　On　(GRACE/GRACE-FO)　are　reported　to　contain　larger　uncertainties　when　only　one　of　the　two　onboard　accelerometers　is　fully　functional,　which　mainly　concerns　the　GRACE-FO　period　and　the　final　stage　of　the　GRACE　period.　Using　these　problematic　coefficients　leads　to　incorrect　mass　change　(rate)　estimates,　especially　over　Antarctic　Ice-Sheet　(AIS),　and　a　replacement　with　those　from　satellite　laser　ranging　(SLR)　is　currently　recommended.　In　this　study,　we　aim　to　discuss　the　possibility　of　improving　the　C30　coefficients　by　extending　the　GRACE-OBP　approach　that　has　previously　been　applied　to　the　estimation　of　geocenter　motion　and　variations　in　the　Earth’s　dynamic　oblateness.　Such　an　approach　mainly　relies　on　GRACE/GRACE-FO　level　2　products　and　an　ocean　bottom　pressure　model,　and　it　produces　compatible　coefficients　with　the　GRACE/GRACE-FO　product　labeled　as　GSM.　With　a　numerical　experiment,　we　demonstrate　the　effectiveness　of　the　proposed　approach　and　identify　the　optimal　implementation　parameter　setup.　The　resulting　C30　coefficient　time　series　is　generally　consistent　with　those　based　on　SLR　and　the　original　solutions　from　the　GRACE　dual-accelerometer　period,　but　with　differences　in　the　annual　amplitude　estimates.　Then,　we　obtain　C30　coefficients　based　on　real　data　and　check　the　AIS　mass　change　time　series　with　and　without　replacing　the　original　ones　with　our　solution.　Our　C30　solution　ensures　consistent　linear　trend　estimates　for　the　dual-　and　single-accelerometer　periods.　©　2023,　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature.