• Let your wife feed Maribel ... but first, for your wife to hold the food bowl & take Maribel through the Sit, Stay and Down routine before placing the food down ... (While Maribel does not have to perform perfectly - she must obey the commands - Just do not hold the command too long and give Maribel a chance to rebel - holding & maintaining the command can come later) ... When Maribel has performed reasonably, place the food down BUT Maribel is not allowed to touch the food until your wife says "OK" (or appropriate release command) ... Then once or twice during the meal - withdraw the food - repeat the whole routine and continue feeding ...
• Perhaps, for the time being, you can stop giving treats or toys to the dog ... All this to be done by your wife. But again - no treat or toy is given gratis ... Before any treat or praise is given Maribel must carry out the the Sit, Stay & Down routine ... Keep the routines short & sweet.

(d) Everytime your dog nips or jumps at your wife, the "NOOOO" command is issued immediately and all activity stops and the pup is ignored until she calms down ... Once the pup calms down, your wife to take Maribel through the Sit, Stay and Down routine ... treating & praising at the end ...

(e) If Maribel is particularly strong minded ... consider attaching a short leash to her collar ... and when she nips or jumps at your wife ... say "NOOO" ... but if Maribel persists, step on the leash ... It's an effective and safe way to calm down an over enthusiastic dog once a "NO" command is given. Do not release the leash, until the command down is obeyed ...

Do remember not to leave the leash on Maribel when unsupervised.

(f) For your wife to participate more actively in training Maribel ... training builds bond between dog and owner ... and more importantly in this instance, establishes responsible leadership over the dog ... It will assist very much if your wife were to spend a few minutes, a few times a day, teaching Maribel some new commands ... whatever they may be. This will give your wife good opportunity to treat & praise Maribel on a more positive note rather than just issuing "NO" reprimands ...

Remember to keep upbeat through it all ... avoid physical reprimands or yelling ... that merely escalates the situation and can make the situation more difficult.

Finally, a tired dog is a happy dog ... very often just providing a dog with sufficient exercise, resolves many potentially difficult problems ...

This is a useful website explaining dominance ... and how to avoid issues of dominance ... http://www.leerburg.com/dominac2.htm

All the best ...

Cheers