Pardon me for being a bit vulgar, but it is a bit necessary because you're headed towards being bent over and used and made to pay for the spit; I can tell because you're even considering certain things. You're operating from a thirsty position and believe that they hold .

>They have demand for their services

How do you know? Do they have demand for their services or do their clients keep asking them for something similar to your product which they don't have which lead them to you in the first place?

>they want to sell our solutions, after polishing it

What polishing exactly is there to make and who does the polishing? I bet that the first and probably the only polishing is to slap a big logo or "Provided by X" company and removing any sent of yours.

>They want to see the option where they would take care of these expenses, through a payroll from they're existing company.

:D :D :D Obviously don't become their employee.

>We however opened a company and want to keep it, but try to involve them in our company with some kind of equity structure or something

Why are you even talking about equity here? If there' any conversation, it should be about you considering hiring them to sell your product, and comparing them to many other organizations who can do that for you. On commission, or something like that. Think of them as a sales organizations, or a recruiting agency and so far they haven't made any sales or provided you with any successful hire yet (job to be done). They claim to have many clients they can sell your product to, your reaction should be "Show me". Start with one sale and see where it goes.

>they are interested in helping us with business development, bringing us clients, and the sales part, so we can focus mostly on implementation/tech parts

Helping? OK, then tell them to bring you a client.

>They have tremendous experience in different industries

How do you know? Did someone there tell you?

>and experience working with big corporations

The pitch started with them selling to smaller clients.

>Also, they have 50 people working for them and they are saying that they can share some of their resources with us.

To do what, exactly?

>For us, it’s hard to find other investments at this point. We will need to bootstrap it ourselves but there is a fear of being late to market because of slow development since we need to keep our full-time jobs for which I get paid 50 euros per hour and my friend \~5000 monthly.

You want clients. They claim they can bring you clients. Talk is cheap; show me the money. You pay them for each client they bring. Payment is tied to a successful outcome: i.e: they make money when you make money.

>We certainly need to give ownership of the company to the other part

I don't have my glasses and thought for a moment that you wrote you needed to give ownership of the company to the other part. I sure hope you are not being serious here.

>Any advice on any known partnership models for this case, or what kind of structure do you guys think that would be the best case for us?

This is not a partnership; this is voluntary servitude. Keep the IP, keep the company, don't be their employee obviously. Any discussion that goes against these should be killed instantly.

It's like you have built a theme park and they tell you they can bring you clients, but you have to give ownership of the theme park, become an employee, and be sent to clean the bathrooms for a paycheck.

Do you have clients and are you generating revenue? Have you already made a few sales?