I added tags to this post to increase visibility.
There are a couple different ways to approach this. Probably the easiest way would be to the calibration levels from one compound (Compound A in your example) to another (Compound B) so that both compounds have identical calibration curves. To do this, navigate to your 'Compound A' in the Concentration Setup task of the Method Edit view and right-click. In the right-click menu, select the option to 'Copy Calibration levels To...' as shown below:
In the resulting popup window, you will be able to select the compound(s) that you would like to apply Compound A's calibration to:
When you exit the Method Edit view after doing this make sure to Quantitate and not Analyze the batch, as Analyze will re-build the calibration curves from any calibration standards you have identified in the batch table.
Another option for you would be to semi-quant Compound B using Compound A's calibration curve. The procedure for setting this up is outlined in the document found at the following link: How to Semi-Quantitate Unknown Compounds in MassHunter Quantitative Analysis
Hopefully this helps.
Super! Just what I was looking for.
Big thank you from here.