Period 8 home with MS 8 and WS 8

Hello, my S2 home has a MS 8 and a WS 8 at the front door, my husband thought to activate both stars was to build a 6 tier waterfall made of stone to place inside our home, not far from the front door, However, the base star 3 is here as well! (and the yearly 7), thus, water will only strengthen the wood and the heavy stone will strengthen the metal of 7 as well.....how can we activate these wonderful 8 stars - I obviously think fire would benefit all but would placing a fireplace by the front door be the wisest choice??

Thanks for sharing your experience and wisdom with us all!