Hi, Marcin,
yes, that’s another way to do it. But I even want to avoid the stress of separating first the female, then the male. Moreover, in a well grown tank it is not so easy to lift the dividing pane and lower it again without wedging the plants in. Lifting the pane results in an undertow – I prefer to leave the pane were it is and give the fry small holes to slip through. I am sure this will lead to many more surviving fry – when even now, with no visible gaps, some fry succeed in slipping through.