Reroute sewer? any suggestion

Hello,
My house has solid cement foundation. No basement. So all the sewer plumbing (kitchen, sink, toilet, bath tub, showers) are burried under solid cement foundation. Lately I had many problems with sewer syste. My house is already 50 year olds. Water backup in bath tub and shower. When it is backup, there is buble buble-up in the toilet. When toilet is backup, toitlet is also backup. right now, the indider plumbing line run from kitchen, connect with bathroom sink, bathroom tub and shower and then go to the exit point outside the home. Another line connect 2 toilet and then go to the ssame exit point outside the home. there is about 30 fts connection from this exit point to city's sewer line

So I am think about rerout the sewer plumbing. I will build the main sewer line outside the house's foundation. It will run outside the house from kitchen position to outsider of 2 bathrooms. And Ended at Exit point outside the home. After that, just has the connection directly from the kitchen out to this outside line. From 2 bathrooms directly out to this outside line. By that way, I don't have to worry the sewer inside the home is busted.

Note, since I am doing the whole major notivated landscaping work: flagstone patio and around the house, fountain, grass and play ground, I want to take this chance to build the outside line sewer line. Later, I have to dig all the flagstone, cement, etc if I have to do it.

Hope I am clear what I want to do.

Any suggetion? Any feedback or comment?

Thanks much,

ndndat, welcome to the forum Sounds like a big job to me (depending on the size of the house and the connection between the different parts that have to be connected outside of it). Do you intend to leave the old sewer as is under the cement and just redirect a new system?