Of there are two known suits either 54xx or 5+5+xx the next free available bid is a relay to ask exact distribution.
The answers are always the same up the ladder as balanced possible, short in the lowest unbid suit, short in the highest unbid suit, void in the lowest suit, void in the highest suit. In any case a fit showing relay is given the first step is to bid a minimum, the rest are automatically maximums. You also give a min max answer to an invitational relay. Only in GF situations with no trump established (still looking for the best contract or slamgoing) you ignore the minimum relay. After showing a minimum the next free bid is still asking for the exact distribution

5 4  5+ 4  5+ 5+  6 cards  6+ minor 5+  Specific Controls asking in suit  

After a 54 there are only 4 distributions left. In the next example a 5 card was shown and a 4 card

Relay after exactly a 5/4
Step 1	5431 singleton in the lowest unbid suit 3 1
Step 2	5413 singleton in the highest unbid suit 1 3
Step 3	5440 void in the lowest unbid suit 4 0
Step 4	5404 void in the highest unbid suit 0 4

If the relay also askes for a minimum or maximum, step1 will show the minimum, step2 will be the 5431 and so on.

Still have to test this... To relieve the 6 card to a 6331 or a 6322 you have to play the 54 as a 5+4. The answers should be. But we still have te decide to play it or not

Relay after a 5+ 4
Step 1	short in the lowest unbid suit
	Step 1	relay
		Step 1	5431
		Step 2	6421
		Step 3	7411
Step 2	short singleton in the highest unbid suit
	Step 1	relay
		Step 1	5413
		Step 2	6412
Step 4	void in the highest lowest suit
	Step 1	relay
		Step 1	6430
		Step 2	7420
		Step 3	8410
		Step 4	9400
Step 4	void in the highest unbid suit
	Step 1	relay
		Step 1	6403
		Step 2	7402
		Step 3	8401

After a 5 5 or better there could be many distributions. I think the next schedule will work the bets, since the exact distribution is shown directly. In the second on there is an extra relay. I have not tested it often and lean to the first solution.

Relay after a 5+ 5+
Step 1	5521 singleton in the lowest unbid suit
Step 2	5512 singleton in the highest unbid suit
Step 3	5530 void in the lowest unbid suit
Step 4	5503 void in the highest unbid suit
Step 5	65 11
Step 6	6520 6610 7510 void in the lowest unbid suit
Step 7	6502 6601 7501 void in the highest unbid suit
Step 8	7600 8500

Relay after a 5+ 5+
Step 1	short in the lowest unbid suit
	Step 1	relay
		Step 1	5521
		Step 2	5531
		Step 3	6520
		Step 4	6610
		Step 5	7510
Step 2	short singleton in the highest unbid suit
	Step 1	relay
		Step 1	5512
		Step 2	5513
		Step 3	6502
		Step 4	6601
		Step 5	7501
Step 3	6511
Step 4	7600 8500

If a 4 card is still possible you have to use this relay sequence. But I seem to prefer to sell the 64 hands as a 5+4

Relay after a 6 card
Step 1	no 4card (6331 or 6322)
	Step 1	relay
		Step 1	6322
		Step 2	6331 singleton in the lowest unbid suit
		Step 3	6313 singleton in the middlest unbid suit
		Step 4	6133 singleton in the highest unbid suit
Step 2	4 card in the lowest suit
	Step 1	relay
		Step 1	6421 singleton in the lowest unbid suit
		Step 2	6412 singleton in the highest unbid suit
		Step 3	6430 void in the lowest unbid suit
		Step 4	6403 void in the highest unbid suit
Step 3	4 card in the middlest suit
Step 4	4 card in the highest suit

If a 64 is not possible, than things get simplyfied.

Relay after exactly a 6 cards
Step 1	Any 6322
Step 2	6331 singleton in the lowest unbid suit
Step 3	6313 singleton in the middlest unbid suit
Step 4	6133 singleton in the highest unbid suit 4

Relay after a 56
Step 1	6511
Step 2	6520 void in the lowest unbid suit
Step 3	6502 void in the highest unbid suit
Step 4	7510
Step 5	7501
Step 6	7600
Step 7	8500

After RKC you could ask up the ladder to ask for the specific controls in a suit. The lowest step asks for clubs, the next for diamonds and so on.

Relay to ask specific controls in a suit
Step 1	No control
Step 2	Q or xx
Step 3	K
Step 4	A
Step 5	KQ
Step 6	AQ
Step 7	AK
Step 8	AKQ