I believe you are asking how to obtain outside capital to complete your music project. That being said you have already got three record deals on the table and top tier management in place. There are two ways I can answer this:
1st: With a recognizable management company and multiple deals to choose from I would suggest they negotiate on your behalf with what is already on the table. These days it is so hard to recoup, that getting your product out there in any way possible so that you can tour and build your audience, is more valuable than paying for everything yourself and retaining all ownership. Labels bring distribution. A publishing deal will not be hard to find if you have a notable label in place. The publishing is an important piece as it is where you can stand to profit the most and retain rights. The label should provide marketing, tour support, PR, radio promotion and so on. Keep in mind that a record deal is like a mortgage, only that unlike a house that once it is paid off it is yours to keep, when you have finished paying off the record expenses the label still owns it.
2nd: Outside funding generally comes from friends, family, and people who have done well in other industries and are keen to invest as a way to be a part of the music industry and have fun along the way. Certainly not as an investment they expect to see a return on. A common source of funding also comes from sponsors/brand partners. Crowd funding/pre-sale platforms are very effective especially if an audience already exists for the band. Grant funding is a very effective way of providing capital.
There are many grants that can be applied for and a quick internet search can point you in the right direction. Grants keep a lot of labels and artists afloat. Whatever you do, you always want to position yourself clearly defining your value. You need to have a clear vision for your brand and have a good understanding of traditional and non traditional revenue comes from.
Hope this helps!