1,614. From Whom a Yevama Receives Maintenance
Hilchos Ishus 18:14
If the deceased left many wives, they all have an equal claim to money for their maintenance, even if he married them one after another (as opposed to simultaneously). The idea of earlier wives having a prior claim doesn’t apply to maintenance.
Hilchos Ishus 18:15
When a widow is obligated to undergo yibum, she draws maintenance for the first three months from her deceased husband's estate. If she is found to be pregnant or was known to be pregnant when her husband died, she continues to draw her maintenance from the estate until she gives birth. If the child is viable, she continues to draw maintenance in the same way that other women do. If after three months it becomes clear that she is not pregnant, or if she suffers a miscarriage, she is no longer entitled to maintenance from either the husband’s estate or from her brother-in-law (who is obligated to marry her). She must file a claim against the brother-in-law to either perform yibum or undergo chalitzah (the shoe-removal ceremony that severs their relationship).