Transfer apps and data from old tab to new tab

Hi All.

Firstly I'm useless with tech. So apologies if this is worded correctly and doesn't make a lot of sense

I have a Google account and a Samsung account and ive always stuck with Samsung as it was simple,my kids needed new tablets as there ones had been for a swim. 1 in a bath the other a sink. Both were Samsung galaxy tabs

remarkably both continued to work (with issues) for some time,

To replace the kids galaxy tabs I bought 2 x Acer A3-A30. I chose these as they seemed good value, had big memory and we're cheaper than samsungs (as I was buying 2 in 1 go)

As stated above, I have a Google account (mainly for play store) the kids tablets were signed into this but had separate apps on each of theor tablets.

In total my son had 2 tabs, 1 was his that went for a swim (galaxy tab 2) the other is an old first generation Samsung galaxy tab. It's on old software and won't update past an old version of Android. Certain apps don't work because of this

My daughter had a galaxy tab 3

All the 3 tabs have different apps that the kids have been playing for a long time, some like boom beach and clash of clans they are joined with friends and have built up there teams etc

How do I get all this data over to their new tabs

I've signed into my Google acct and selected an old tab for the new tab to get the info from but not everything seems to have come across and my son has 2 tablets I Need to get the data from

How can I go back to the old tablets from the new tablets and get the games/apps with all their saved data etc

Kind regards