John,
Really sorry for the struggles you and your wife are dealing with!
The supplement you described should not interfere with L-dopa absorption as long as it is not high in protein.
This explanation may help; Certain amino acids such as L-tyrosine, L-phenylalanine, L-tryptophan, and L-leucine which are present in most proteins tend to interfere with L-dopa (which is also an amino acid). They don't totally block the passage of L-dopa from the intestine to the blood, or from the blood into the brain, however these amino acids all share the same "transport system" to get through those barriers, so they compete with one another in the process. (Think of a crowded turnstile.) After eating food with lots of protein in it, the food amino acids released upon digestion flood the intestinal "turnstiles". Because their concentration is much higher than the L- dopa from meds taken near the same time, the L-dopa passage into the blood will be greatly slowed. The same scenario prevails if the dietary amino acids and the meds L-dopa reach the "turnstiles" at the blood/brain barrier at the same time. This is the reason to avoid taking L-dopa near the time of eating food with high protein content.
It is important that your wife's diet include some protein, of course, but foods such as cheese, eggs, meat would be best limited. Gelatin is one protein that is somewhat low in the "problem" amino acids.
I am a thin person who has a problem keeping my weight up, and my neurologist encourages me to keep supplement drinks like "Boost" and "Ensure" on hand, and consume them following a regular meal.
I hope that something I've written might be helpful, John. Feel free to PM me if you wish.

Robert