Marcelo,These direction apply to Finale 2001. It may be different in 3.7.1r2.
To create a pickup measure anywhere in the score:
1. Enter the pickup notes in the measure. Switch to Mirror Tool.
2. Click the measure. The Placeholder dialog box appears.
3. Specify how far the pickup notes should be pushed from the the beginning of the measure. An example: If your time signature is 4/4 and your pickup is 3 eighths, you should set the placeholder to 5 eighths. Click OK. You might need to rebeam with the Mass Mover Tool.
To create a mirror measure:
1. The measure must be empty. If you are in doubt, select the measure with the Mass Mover Tool, and press the "clear measure" key (Windows: the Backspace key ; Mac: the Clear key on the numeric keypad).
2. Switch to Mirror Tool. Click the measure. The Tilting Mirror dialog box appears.
3. Use the arrow buttons to navigate to the source measure. Clicking ^ will take you to the same measure in the staff immediately above. Clicking < will take you to the preceding measure in the same staff. The source measure can be a pickup measure or an ordinary measure.
4. If you don't want all the notes of the source measure, drag the dotted vertical lines until they enclose the source notes you want. Let's say that you only want the first 3 eighths of the measure. Therefore press the handle at the top of the right, dotted, vertical line, and drag it to the left to deselect the last 5 eighths of the measure. Now you have filled out the first 3 eighths of your (previously empty) mirror measure. Let's say that you want the remaining 5 eighths of your mirror measure mirrored from another source measure. Therefore click the "Next" button, navigate to this other source measure, select the 5 eighths, and click OK twice to return to the score.
To edit a pickup measure or a mirror measure, switch to Mirror Tool, and click the measure.
By The Way: don't select partial tuplets. The whole tuplet must be selected, because Finale stores the information that the tuplet is a tuplet in the first tuplet note. If you e. g. select the last triplet quarter of a quarter triplet, you will get an ordinary quarter instead of a triplet quarter.
Peter