Re.

After TiHao left, WonPil sold the house in Shiirhuang where they were living and moved with the children to an apartment for rent.
They stayed in that apartment for a few years, until WooPil decided to buy the house by the sea, that needed a lot of work to become inhabitable. And the house was bought by Wuxin, who leant the money so that WonPil wouldn't risk to lose the house to someone else.

That's the canon story. From this point on, start the changes to fix the discrepancies from the changes in the story.

Due to the fact WonPil's and TiHao's children were born in a time in which homosexuality was even a crime — and due to the fact they were born from two males — the children were registered as only TiHao's. WonPil insisted on that, because it was the lost sensed way: TiHao was a big deal, a powerful man nobody would dare to mess up with, while WonPil was a nobody. And they had to also he recorded as children of "unknown mother", due to the fact they couldn't say they gave birth to them, not to the public registers.
This, for the most part, didn't lead to any kind of troubles, until TiHao left and ShiHao set his eyes on WonPil.

Since WonPil refused him, ShiHao took profit of the situation with the children to try to force WonPil to move with him. ShiHao was still a well known and famous IA that most people wouldn't dare to displease but most importantly: he was the closest living relative of TiHao's children, for what the law knew.
That meant that when TiHao left, ShiHao could use his position to literally take the children away from WonPil. After all, he was the uncle and to the law, WonPil was nobody to the kids, since he was never even officialised as a concubine in Qiu family.

ShiHao took away the children, forcing them to stay with him in his manor. And it wasn't a happy time for them, especially the younger ones.
In order to be closer to the children, without necessarily throwing his life away, WonPil asked for a small loan to Jun and used the money to buy that old house in Fengshii, as it wasn't far from where ShiHao lived.
The matter significantly slowed down the improvements to the house by the sea, but the children were everything and WonPil could certainly not leave them in the hands of that sociopath.
What happened between ShiHao and WonPil is unknown. Fact is that the law couldn't help with the matter, so it could only be solved by either getting rid of ShiHao — which is something WonPil wouldn't even consider — or by convincing the man to step down.

Before the matter could come to a conclusion, Elton's possession and the ritual happened, so ShiHao died first.
That matter could also have been the reason why TiHao had that brief appearance during that time, to solve the mess ShiHao caused, although there was no need for it, in the end, as both ShiHao and WonPil died and couldn't keep the children with them.

After WonPil's death, his children made sure to ultimate the house by the sea and keep it well preserved. That was the best they could do to honour their father's last wish before he died, although he never had the chance to see the house finished nor to live there with his family at all.