
Your partner is right. Be firm, put food down, leave it ten minutes, pick it up again. Dont put it down again until the next meal time, and dont feed titbits inbetween.
If you free feed, you dont know how much they actually are eating each, (which can be a problem if one gets ill, or in your case where one is younger and needs more food), and you are creating a very fussy dog.
Pick your brand of food, stick to it, and dont give in, even whippets arent daft enough to starve themselves (and i know about fussy dogs, i have a saluki x here!!!)
Em