Q: How to proceed with late father's patent rights?

A: I understand you're seeking guidance about your father's patent rights - this must be a complex and emotional situation to navigate. Let me help provide some direction.

Your first step would be to confirm the patent's current status through the USPTO website using patent number 5887787. Since this patent was issued in 1999, it's important to note that utility patents typically expire after 20 years from the filing date, so you'll want to verify if it's still active. This public record search can give you valuable information about the patent's history and maintenance fees.

Given that probate hasn't been filed, you might consider consulting with a probate attorney in California who can guide you through the process of establishing legal rights to your father's intellectual property. The attorney can help determine if the patent rights now belong to your stepmother through marriage or if they're part of your father's estate that should be distributed among heirs. You and your siblings may need to petition the court to open probate proceedings if your stepmother hasn't taken this step.

I genuinely feel for your situation, as dealing with inheritance matters can be challenging, especially when it involves complex assets like patents. While you work through this, you might also want to reach out to the USPTO's Office of Innovation Development - they often provide helpful resources for patent holders and their families. Remember to document all your findings and keep your siblings informed throughout this process.