Let's see how to assign a spectrum containing a mixture of two compounds and how to extract the spectrum of each compound from the mixture.
Assignments
First of all, load your dataset with the applicable molecular structures (you can download the Mnova document from here). 
Make the assignments as usual. In the example below we have assigned the atoms to the applicable peak (for more information about how to make assignments, see this tutorial): 
Follow the menu ‘View/Tables/Compounds’ and select a different color for each molecular structure (purple for Ethoxyethanol and red for Caffeine): 
Follow the menu ‘Edit/Properties/Assignments’ and make sure that you have checked the ‘Use Compound Color’ box: 
This property will show the assignment labels with the color that you have selected for each compound (purple for Ethoxyethanol and red for Caffeine): 
Extracting spectra from the mixture
Now, let´s extract the spectrum of each compound from the mixture. Run an automatic ‘Peak Picking’ analysis and follow the menu ‘View/Tables/Peaks’. Click on the ‘Select Peaks’ button and drag&drop over the peaks which belong to Caffeine: 
Finally, click on the ‘Set Compound’ button of the Peaks Table and select ‘Caffeine’: 
Click again on the ‘Select Peaks’ button and select the peaks of the Ethoxyethanol. Next click on ‘Set Compound’ and select the applicable molecule. You will get the applicable peaks labels for each compound as you can see below: 
Finally, click on the ‘Filter’ button of the Peaks Table and select ‘Peaks assigned to Caffeine’: 
You will see how the Peaks table will only contain the peaks of the Caffeine. Finally click on the ‘New Spectrum’ button to generate the ‘Caffeine’ spectrum: 
Do the same with the ‘Ethoxyethanol’ to get the applicable spectrum 
You can download from here the final document containing the mixture and the extracted spectra of each compound.
