Is there such a thing as a "guarantee" by a Schengen resident

A sponsor can make an offer to provide economic support and member states are allowed to have instruments that they can use to make the offer binding. You seem to have already examined the instrument the Netherlands uses and have concluded that it does not suit your needs. You want to know if your sponsor can submit an attestation of good character on your behalf.

wondering if we can make something like this work in order to strengthen our case?

No full stop. A sponsor cannot guarantee that an applicant will honour the terms and conditions of their visa. The rationale is quite simple: people are not telepathic and so a sponsor has no way of knowing your intent. Moreover, it is empirically sound to state that close friends and relatives will not turn an abuser over to the authorities (that activity falls to neighbours and co-workers and spurned lovers who are not generally sponsors anyway).

Instead, close friends and relatives may be prone to harbouring and this is something to consider very carefully in how your material is presented.

There is nothing in the Visa Code that says a person is forbidden from submitting an attestation of good character on behalf of an applicant, but this type of evidence is ignored and in the worst case demonstrates naivety in understanding how visa decisions are actually made. There are some horrible examples floating around on the net; avoid them.

This might sound unnecessary to most of you but we're from a country that isn't very well received in Europe or North America, so....

There are some nationalities where their performance history is unfortunate. This can make things more awkward for innocent and well-intended applicants. One 'work-around' that I have used successfully is to elaborate/expose an elevated social standing for the applicant and his family. Maybe such a strategy will work for you.

Unfortunately, having a family member in the country you are wishing to visit usually raises more red flags than anything else. The immigration officer reviewing your visa application is likely to think that you are trying to immigrate illegally in the country to come live with that family member. Therefore, I do not think that using them as a guarantee that you will leave the country will be effective in any way, nor that such a concept might even exist.

The only way to prove that you intend to leave the Schengen area within the stipulated time, is to demonstrate that you have strong ties to your home country. These include all sorts of commitments which indicate that you live a stable life in your home country and are not looking to emigrate anywhere, such as and not limited to:

• A stable job
• A full-time school/university/course to attend
• Economic interests / assets / real estates / property
• A family / spouse / elderly parents / relatives
• Social ties

It is obviously up to you to detail your situation in your visa application, and to bring all valid documents supporting your case when you attend the interview.