QU---Will 4 tweeters per crossover have a longer life than just 1 using 500 watt receiver based on above specs? OR should i buy a new crossover? Thanks for replies.
Your question has already been answered, just not the way you wanted. A crossover slope of 6dB per octave does little to protect your tweeter(s) from damage. Multiple tweeters are not the solution because 1) you will introduce comb filtering, and 2) they'll still have midbass bleeding in because your crossover slope will still be too shallow. You'll burn them up sooner or later. Buying a new crossover is not the answer either, because an off-the-rack crossover will not be a proper match for your drivers and cabinet. Designing a crossover for the drivers you have requires lots of knowledge, experience, time, patience, trial, error, measurements, and dedication in general. You could patch in 18dB per octave crossovers, but will they be at the correct frequency? Would it combine with the natural rolloff of your existing drivers to net you 24dB per octave? Will your tweeters comfortably play low enough that you can shove the breakup frequencies of your 8-inch mid driver down -20dB? Have you measured the raw response of your mid driver to know where that breakup area lies in its range? Will the drivers be properly phase matched? Will the highest frequencies of the tweeter be properly attenuated for baffle step compensation?
It doesn't matter how often you ask that same question or the manner in which you rephrase it. The answer is going to be that this is a failed project, and we cannot help you salvage it. I'm sorry that's not the answer you wanted, but it is, regretfully, the correct one. For a very brief intro into the knowledge you seek,
see this post.
Now, if you're interested in a more worthwhile project where you'll build something you can truly be proud of without having to become an expert on speaker design, we'd be delighted to help you there. It'll require starting from scratch, though, and choosing specific components that have been modeled into a tried-and-tested design.