Let's call the two boards i1 and i2 and the final board fin. For simplicity let's assume i1 is almost the final board, needs only a=20 small section from i2.
1. open i2, delete everything except the small section needed, save as=20 (e.g. tmp.lht)
2. open i1, menu: file/import/Load layout data to paste buffer, open=20 tmp.lht
3. if the layer stackup of i1 and i2 does not match, you may want to=20 change the layer binding recipe while tmp is still in the buffer with=20 menu: buffer/layer bindings
4. paste the buffer wherever you want
5. save as fin.lht
Note: if you prefer side-by-side view, you can run 2 instances of pcb-rnd in parallel and do step 1 in one instance and steps 2, 3, 4 and 5 in the other one. This could be usaful if you want to transfer in a lot of small portions.
Note: this does not work at the moment due to the bug John reported;=20 will be fixed soon.
1. open i2, select the parts you want to transfer; if it's a complex=20 section that is hard to select, you can also remove uninteresting parts=20 first
2. copy to buffer
3. now that you have the interesting part in your buffer, you can just=20 load i1, discarding the changes to i2. The content of the buffer is=20 preserved.
4. do the buffer layer recipe changes if needed
5. paste
6. save i1 as fin
Note: there are actually 5 paste buffers; you can select the active one in the buffer menu. This means you can even take and transfer 5 different sections by repeating step 2 and 4 and 5 with different buffer while doing only one of step 1 and 3.
1. load i1, remove the uninteresting part and save as tmp1.lht
2. load i2, remove the uninteresting part and save as tmp2.lht
3. start a new board
4. load tmp1.lht into the paste buffer (same as method #1, step 2)
5. if needed, do the buffer layer recipe revision (same as method #1, step 3)
6. paste
7. repeat steps 4, 5 and 6 with tmp2.lht