I never even knew there was integrations, for other than a “predefined” heating system
There are so many aspects, starting with the Physical System ( Pipes(and diemention of same , pumps , valves, watertank(s) etc. etc.
And as you have an old system you want to “function” in a new/better way, i can understand there is no Integration for such, as all households with own central-water-heating-system looks ( And works ) different in all aspects above( + Some more "variables )
I.e Do you have a " technic/or multitank" as they also are called, or only a single, which also have to provide hotwater to both floors, where you can control the water in layers, or only the " 1 way in, 1 way out " ( Im pretty sure you don’t want to pump 70degreC water into your UFH.
i.e Do you have to 2-Pipe or 1-Pipe system , all around , do you have Thermostats on the Elements in bedroom.
Is it an open or closed system, etc
There’s alot more to take into consideration, so i guess you can see that your “opening Topic” is not of much Help, trust me your not the first one in here who have started like that ( With an idea ) , and hardly anyone can give you good advises or ideas on the “limited” description of your System etc. ( Like how was it working before/or currently etc )
As they also have no idea anything in regards to your “usage” big family, “with no limits”, etc, and “Boiler” etc.
Again, if it’s not a “pre-fap” House and System, everything is relevant and Different
Below is the latest post i’ve seen in here, from a guy which seems to be in the “same boat” as you, ive been there years ago(decades), and ended up rebuilding , redrawing and “Designed it” to meet todays demands and rules n laws, and needs
NOTE: lots of work and New “Utilities” , basically only the main-pipes(in the basement) left of the old system 
Advice on setting up hot water tank automation .
Keep searching and reading, there are also dedicated Forums DIY, where you can get ideas and answers, beside the knowledge of how such system works(Nature law, etc.)