Question on Strategy to Purchase Family Home

Hello All, 

This is my first post so forgive me if I've posted this in the wrong section. I am looking for advice on the best strategy to purchase/obtain my parents current home as they are planning to move into a bigger home. Looking for advice / guidance on how best to make this deal any and all opinions / comments are welcome! Thank you in advance. 

The current situation:

Parents have owned them home for 20+ years. The loan is a conventional loan with $189k remaining balance and a 2.99% interest rate. Their current monthly principal + interest is $1700 / month. The current home zestimate is $522k. 

The Goal: 

To either purchase or obtain the home with the existing monthly payment and/or interest rate / property tax for myself and pay out my parents their equity outside of the home loan for them to use on their new home purchase. 

My situation:

Currently own 1 home with a month principal + interest of $2600 / month. Annual income of $116k

Options I have started to Explore: 

1. Assume the current Home loan from my parents 

 1A. Unable to explore this further as their loan is a conventional loan which does not allow assumption

2. Write a new loan with a gift of equity from parents to drop home loan amount down to meet the $1700 / month with today's interest rate

2A. Exploring this option with Loan officer to explore what can be done. Looks to be a viable option so far

3. Put the home in a trust and have myself & parents under the trust to keep home loan as existing

3A. Have not explored this option yet, but plan to.