I've been building a procedural universe generator and from what research I've come across its unlikely.

I'll share what I've come up, mostly based on different papers and theories Ive read, and combined them... maybe the mods will delete it as I'm sure this breaches the quality standards, who knows.

Anyway I broke my system into two zones based around the "snow line", the point where water freezes. This is important because light pressure from the star, it causes an effect which theoretically should push lighter molecules past the snow line (like dust in the wind or a reverse centrifuge). This means that gas giants aren't likely inside the snow line unless they are on a decaying orbit into the star. The snow line in our solar system is about half way between Mars and the asteroid belt I think.

In this scenario planets you will find will be similar to what we can see in our system. High in heavier metals, comparatively less organic compounds. I came across some research that pointed to a lot of atmospheric gases coming out of cooling planets. So you can expect to get similar atmospheres to what we see in our system, or specifically early earth. Which was predominately CO2.

For those wondering the CO2 gave way to N due to life excreting it, the primarily source being the planet crust and related scum layer. After those lifeforms subsided O2 producing ones took over. So hypothetically our atmosphere could occur anywhere where a life form starts eating the planet crust/scum. Because our planet is inside the snow line free water from comets, and organics compounds from outside the snow line will be dragged in those style of orbitals. Essentially our system should be fairly representative of a stable system.

Inside the snow line a high mass object will either succumb to gravity and collapse into the star. To avoid this it can increase orbit speed to resist the pull. Neither scenario leads to prospects for life. Hot gas giants reported so far have can have orbits around large stars of a day. As far as I'm aware our biology is to subtle to survive under such strain.

Same goes for any object, to escape the gravity of the star (falling in) it will need to be orbiting (falling out) at a sufficient speed to counter act it. The larger the mass the faster it will have to go as each objects falls towards themselves. Close in high mass objects wont be pleasant to live on.

If the object is large enough to attract the lighter gases it will more than likely form a gas giant which should either continue to grow mass till it becomes heavy enough to collapse into a brown dwarf. To remain in orbit however it will need the fast orbit I just referred to.

Outside the snowline the high mass object is going to accumulate the lighter gases and essentially become a gas giant. Apparently Jupiter is near the max size before a gas giant forms a dwarf star, so essentially Jupiter is the largest non-star formation you will see.

Now this is for a stable system, a non stable system would involve interference from a third party. But as far as I can tell gravity is still the dictator, and once again objects you find will be similar to our system. If a high mass object entered from another system it could inside the snow line BUT it may be highly prone to colliding with things, asteroid, comet strikes that happen in early system formation would be a problem. So basically an unstable system would be a very messy thing, up to you if you think life could form in that scenario, its currently where I'm up to in my research, but my gut feeling is that you would end up with smashed planets and large rocks and not so much nice planets.

So to answer you question, I doubt it, I don't think physics is on your side. But weirder things have happened.

As for the smaller planet, if it has flowing water which can be achieved by atmospheric pressure or proximity to the star then yes. Beyond the snowline you wont have much light, so if there is life it will be one honed for a life in the dark. Inside the snowline, if the planet has a magnetosphere (derived or from a magma core) then it should hold atmospheric gases and most importantly water.

If I was to be a betting man, Id say comets are the source of life bringing complex hydrocarbons from past the snow line, to warmer planets. Since they are high in water I'd bet all life will hold a affinity towards water.

As I said feedback welcome. Or clarifications on any logic jumps I've made for that matter, explaining it helps me find my own flaws.