How does our developer's day job impact our IP?

You haven't mentioned whether the day jobs are similar to the jobs that they are performing for you. In any case, you may need to consult a contractual attorney so as to effectively draft a contract which your developers can present to their day job employers for signature to the effect that any products developed by them, not on day job company time, is not the property of the day job employers.

Hi,

Some general information: There are federal laws of IP ownership and overlapping state laws. Check your state's labor codes on employee IP ownership. Some states like California have specific rules. If there are none for your state, go to the next step and check what the case law says about employee IP ownership. Most states have an employer favorable rule set. Mainly, if the work you are hired for is similar (or foreseeable) to the IP you are generating apart from the employer, they could very well own it regardless of whether you use your own resources or time. Check your employment contracts for specific wording as well. Note: the contract wording may or may not be enforceable. This ownership inquiry is very fact specific and it needs a through going over. The IP ownership you want to make sure you get right, because you don't want to work for the IP and not own it, or be entangled in suits etc. Contacting an attorney in your state who has both the IP and employment experience can help you answer the matter to the details you need/want.

Hope this helps!
Mary